CIC说的:
Please note that a PR card or travel document is required for all permanent residents returning to Canada on a commercial vehicle (plane, train, boat or bus).
If you return to Canada in a private vehicle, the PR card is not mandatory; you can use your immigration paper (i.e. Record of Landing (IMM 1000) or Confirmation of Permanent Residence (IMM 5292)). An officer will ask you questions to see if you meet all of the requirements before allowing you to come back to Canada.