I'm a Chinese citizen and now resident in Canada. I want to apply ITIN to use tax treaty on the income from resources in US. So I don't need any tax return form because of Exception #1, is that right? Which tax treaty should I use? US-China, or US-Canada, or can I choose?

If you are a resident of Canada, paying Canadian taxes, then, for treaty purposes, the U.S.-Canada tax treaty applies.

Thanks for your prompt answer. If I don't use the treaty, should I pay taxes to both US and Canada?

You will pay the U.S. taxes, but I believe Canada will give you a dollar-for-dollar credit for that paid tax so you are NOT double-taxed on the same income.

However, I am NOT a Canadian tax expert, so you need to contact someone who IS expert on the Canadian tax system to be sure.