Impossible. Complete loss of face. Especially as they say that we smell like hippos and they smell like turtles. If you reverse a stereotype they go ballistic. I have a coemployee who likes to shove her face directly into my notebook at the office and see what I'm doing, and her breath in unbearable.

But I just have to accept it as a part of China's beautiful genetically and spiritually superior five thousand year culture. Monkeys like us could never understand their advanced ways

Dropping the deodarant on the desk is one option.

The other option just say I have some new deodarant and say he should try some and spray some on him.

Or 

Forget the face and just tell him directly that his smell is bad and should take care in his body.

Yeah like brisguy said.

Take a bottle of cologne into work with you one day.

Talk to your employee; "Oh hey try this new cologone I bought"

Get them to spray it on themselves (Or give them a hand by spraying a 'liberal' amount onto them) then say;

"Oh wow you smell so good! You should use this every day, handsome boy, you will get all the girls"

In general, Chinese people do not use deodorant at all, much less  a cologne or mouthwash.  And yes, sometimes they do not smell themselves at all, and have no idea how offensive their body odor could be to others.  But that is their way of life.

If it does bother you, a veru private short chat with the guy, pointing out to him or her in a nice way that sometimes the smell really bothers you to the point of almost making you sick could be a solution. 

explaining health benefit of cleaning or hygiene. another point is to show them in picture different diseases or dirting things associated with dirt. if your pocket is big gift them with mouthwash, good tooth paste, expensive toothbrush, nice shampoo, branded perfume, and etc.. 
if your pocket is small so talk to them in a distance or better stop breathing when you are near them. change chinese is harder.

I think u will eventually just distance yourself from him. Changing his habits won't happen for about 5000 years.

Scream "PeeeeeYUUUUUUUUUUUUUUU!!!!!!!" While pointing at him!
I cannot think of any polote way to be honest. I guess Dharmas answer is the best (i.e. most Chinese) way.

Just asked my wife this question. She said that its easy to solve the problem. Just utter a blanket statement within earshot of others like, "Hey, does anyone else here smell that?"  If you do that a few times, the guilty will get the message and will not "lose face."

i think its not actually body hygene..  its some vegetable they eat... i think its leek?