Registered nurses are on the list of 38 occupations that qualify under Category 1.
http://www.cic.gc.ca/english/immigrate/skilled/apply-who-instructions.asp#list
However, nursing is a regulated profession, and is regulated at the provincial level. In most provinces now, registered nurses have to have a bachelors degree (4 years). Do not know if this would prevent you from qualifying, however, you would not be able to work without having your credentials evaluated or without getting licensed in the province where you intend to settle.
Your best source of information is here:
http://www.cna-nurses.ca/CNA/nursing/becoming/international/default_e.aspx
As well, there are many other nurses on this forum, you can search the forum.