You can apply for a China visa from the China Embassy in Ottawa or China Cosulate in Calgary, Toronto or Vancouver.

My travel agency told me that I can't apply in Canada unlness I have Canadian Permanent card or has to show marriage certificate (which we don't have yet. we will have when we go back to china together). My agency called the embassy and they said NO, can't. so I'm not too sure. I'm currently working in Canada under work permit and holding Vietnamese passport. so if your answer is YES, that means I can take it as guarantee? thanks

Ms.Do, if the embassy said NO, then you may not be able to apply for a visa in Canada, since the China Embassy in Ottawa hawe the final say to your visa application, while the comments here are just travellers' personal experience or ideas which can't be considered as any guarantee.