Under the Immigration and Refugee Protection Regulations, overstaying in Canada will result in a Removal Order(遣送離境令) issued against you. In this case, if you do not leave within 30 days, it will become a Departure Order(遞解離境令) that will bar you from entry to Canada forever unless you apply to the Minister of CIC for a permit.
If you have already overstayed, you should immediately leave Canada as a removal order can be issued to you as you read this paragraph.