Not so sure but my Chinese friends told me this:
1. They don't have sex education in highschool or college.
2. They don't have prom or school socials or whatever.
3. Relationships are forbidden in highschools.
4. They don't study human reproduction in highschool (5 of my friends confirmed this)
So given this, when they finally enter relationships, many of them don't now what to do or if they do, don't know how.
My girlfriend told me her former roommate only found out last year that prolonged kissing doesn't cause pregnancy. And her first boyfriend (chinese) didn't know where 'it' was. 
This is the situation here. Sex is just one of those mysteries many here only start to understand once they're married and even then it's still an elephant in the room.
A brazilian friend of mine told me he once slept with a married woman here. In her 5 yrs of marriage, she'd never had an orgasm. She immediately wanted to divorce her husband and go with a guy 6 yrs her junior.  
Oh yeah, and porn is heavily blocked here.

In my opinion, sex in China is widely practiced, yet totally unknown in the technical aspect.  When women are fertile, their parts and erogenous zones, the curse, etc, is just a bunch of "old wife's tales" and heresay.
I am surprised many men, and also women, have no idea what the clitoris is, or her "G-spot", or what they are good for.  Many never even experience an orgasm while having sex.  In this aspect, most are submissive while at intercourse, and hold a bunch of crazy ideas, like do not touch me unless you wash your hands because I do not want to get hepatitis.  Or sex during menstruation will make you and them sick.
Other than that, I do believe they hold sex as just a physical necessity, like I may be thristy and drink a glass of water, or hungry and eat.  They may have the need, and find someone (makes no difference who) that they like and bang, they do it.  Yet others do it because most persons their age in foreign countries have sex.  Maybe the fact that there are no religious principles bears some on their attitude towards sex.

To me it is really enjoyable to chat with locals about this subject matter, it really amazes me some of the wild notions and stories I hear this way.

It is my guess many women in China do not enjoy sex (not that they do not like it) because they do not enjoy it.  Most Chinese males will mix sex with physical abuse, especially if drunk when arriving home.  I knew one girl of about 35 years who was married to a fellow here, and she could not have sex unless you beat and spank her first.  We did not last long together, I am not really into that.

Another, 23 years old, had sex with a friend at a party and got pregnant.  She could not understand why because it was two weeks after she menstruated !.  I just smiled at that.

I don't really talk about sex with my Chinese friend, but other things like menstruation...wow, some of the crazy things she's told me. Her doctor said not to take any pills for cramps, just eat brown sugar? Don't drink cold water because it will make the cramps worse? What? I know that when I started high school, I was very naive and couldn't say the word "sex" any louder than a whisper, but I wasn't this clueless. The lack of knowledge here worries me, not just about sex education, but about health in general. If you're not informed, you can't make the best decisions in your life. You won't know the dangers, so you can't avoid them.

Despite the awkwardness and limited nature of sex education at my high school, I'm glad I had that class. I now feel well informed about many things, and although I choose not to have sex, I know it is the best decision for me. I think all their problems come from lack of knowledge, and it's a real shame.

I think that since many expats are guys, they can talk about these kinds of things with Chinese guys. But the girls? I don't even hear a mention of sex at all, and I'm sure that if I brought the topic up, I wouldn't get any answers. Even if I did, they might not be the truth. This is such a stark difference from my time in college, when my friends (guys and girls) and I would often joke about sex and other things that would never be spoken of here. I think most girls, at least at this place, think that sex is something that comes with marriage. I would think that if you don't know anything about sex, you wouldn't know all of the things that could come from it, good or bad. They're just left in the dark.

Sex is part of our life...Every country ppl love it...it's our physical nature...

If you wonder why sex isnt seemed important in China socity, you are definitely wrong. The only difference between Chinese and non Chinese is we don't talk about it openly.

China society (since Confucious)  emphasis  moral on the inner beauty. Western society (since Greece) emphasis the outer beauty more. This is why westerners all seemed bold to talk about every parts of their body (incl sex), but Chinese seemed shy to mention these things. You cant say Chinese is wrong about sex. The reason I want to say sometimes you have to take porn industry etc western culture had transformed sex idea (it's like ppl food!). I don't wanna say it's wrong, but it misleaded the idea about "real sex" (2 ppl making love).....So when Chinese enjoy the normal sex, in westerner eyes it's no passion....This is something ridiculouse~~~~

Anyway...Thedude seems not had enough girls yet:)....Either western girls or Chinese girls at theri early 20's have same idea about sex..when tohave sex...who they will have sex with..etc....(rarely situation some girls are just sluts type)...When the girl is aging...the idea about sex will change...ALL OF THEM definitely enjoy sex....the difference is some of them talk, some of them don't...some of them will be a slut later..some of them are bitches..

Guys..you are inexperience...be prepare for some Chinese girls you maybe couldn't handle well in bed!!...(j/k)

Pre-60s... sex was pretty utilitarian for many women. They weren't open about it, couldn't really discuss it with their partner or their friends because it was taboo. It was pretty much a good time to count the dust bunnies and cob webs on the ceiling tiles. It was a means to get pregnant and considered their duty to keep their husbands happy.

Viva la sexual revolution!!

If you talk to women who've lived through both eras, many say that sex was MUCH better as they got older, because they actually learned to talk about it, tell their partner what they liked and didn't like and actually enjoy sex.

We've had the benefit (YES I SAID IT!) of pornography and open conversation to help expand our creativity and willingness to experiment.

IF chinese women seem a little... aloof... give them time. There hasn't been a sexual revolution/revelation yet. They'll get there TBH, I think the experiences with foreign men will help them break out of their shells, and discover government issued sex is so... 5000 years ago.