I have got a canadian PR, and currently in Houston texas, under H1B.I would be going to canada and living there for 3-4 years to get my citienshi

I believe your question has to do with timing. If you are a native of India or China, you would probably want to start your green card application is soon as possible in light of the long visa wait. If from a country without a long wait, you can take the latter route. If you have completed 1.9 years of your H-1B, you have another four years of maximum H-1B stay, but would have to file and have approved a new H-1B through a petitioning organization if you are thinking of reentering the US under H-1B status. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.