On one hand I know of no limit as to how much you can have on you, but I am sure somewhere there has to be one.  In exiting China I do remember a limit of 6,000 RMB cash on you.
Since you mention dollars, ther is a limitation of $ 10,000 in cash or negotiable documents on you when leaving USA.
I have been entering China since 1997 or 98, from 2 to 4 times a year, and never was asked how much cash I had on me by anyone.

Its 5000 USD if memory serves, coming into China  from the US (undeclared). You can bring in  as much as you want , but you need to declare it on the form.

If its more and they find it, and you dont declare it, they can confiscate it.

Ex pat is right, its 6000 RMB!

Expat is correct, under 10,000 USD can leave the US undeclared. If its 1 penny over,and you dont fill out the form, you dont pass go, it gets confiscated and you go directly to jail!

In the US, they count up all money from all countries...and add the total to get to that 10,000 number. I dont know how it is in China. They (US) count negotiable instruments too (bullion, bonds, checks, etc. etc.). Its the US so they try to get to 10,000 any which a way they can!

They even count the loose change in your pockets just hoping it adds up to over 10,000. Those customs  guys are just  as bad as those TSA gropey feely guys! Only difference is the customs guys are better educated and dont have the extensive criminal records the TSA guys do!

You can take out as much as you want from the US, but you need to declare it, so Joe IRS can give you an audit (with rectal scope) later. :) 

BTW, they look that closely in the US , due to drug money. They look for it on the scanners, I bet they even train them dogs to smell greenbacks!