If a US green card holder marry a Canadian citizen will she become a Canadian citizen?
No. Assuming that there are no other legal impediments to your
entering Canada, you could get into Canada. You could apply for
permanent resident status - something you should do BEFORE you
arrive in Canada. Being married to a Canadian citizen would
probably be a big advantage. Getting Canadian citizenship is a
whole other process. Before you can apply, you have to have lived
in Canada for three years without interruption or, in some cases,
for three of the last four years. If you meet all of the
requirements, THEN you can become a Canadian citizen. Being married
to a Canadian will help with that. But marrying a Canadian will NOT
automatically make you a Canadian citizen.