If your Canadian Visa is expired, you are an illegal resident in Canada. (sorry, but it is the fact).
Why are you still in Canada? Waiting for marriage?
You can't marry in Canada (or at least Onatrio) because you don't have a valid Passport to proof your identity and nationality, unless the law is changed.
Suggestions:
1. Leave Canada (and return to China because you can't go elsewhere without a valid Passport) as soon as possible. Otherwise, if Canada Immigration department catches you and finds that you stay in Canada illegally, you will have a bad record. Then you 'may' have a problem to immgirate to Canada in the future even if you marry a Canadian or landed immigrant.