Keeping your permanent resident status
Your permanent resident status allows you to live in Canada, but there is also a time limit on how long you can live outside the country. To keep your status as a permanent resident, you must live in Canada for at least two years within a five-year period.
For further information on residency obligations, please see Appendix A of Applying for a Permanent Resident Card, which can be found under Find an Application Form or Guide in the I Need To… section of this page.
http://www.cic.gc.ca/english/newcomers/about-pr.asp