Read the rules and follow the rules, otherwise you may get in trouble. At the Canada Custom, you can bring in $10000 CAD or other funds equivalent to $10000 CAD or less without claim. If over $10000 without claim, the Custom has the right to take your money away. You may also be on the black list (as a potential dru pusher or dealer). Be aware and careful, these customer officers are very experienced.
When leaving China, I know you must claim if you have more $5000 USD; otherwise ... you know if they find it out.