I have not live in The U.S. for 3 years.
I still own and pay on property, but reside in Canada.
Is my rent in Canada a deductible expense?

“I have not live in The U.S. for 3 years.”---> What is your visa status?
“I still own and pay on property, but reside in Canada.”---> As long as you are either US citizen or a US resident for tax purposes, then In general, your expenses of producing rental income in US are tax deductible against rental income, regardless of how much you earn. Such expenses are NOT deductible directly against your other income; I guess, in general, you’ll need to complete a Schedule E , Also, you may deduct ordinary and necessary expenses for renting or leasing property used in a trade or business. An ordinary expense is an expense that is common and accepted in the taxpayer’s trade or business
“Is my rent in Canada a deductible expense?”--->No, I don’tt hink so; you can’t deduct the rent expenses in Canada on your federal form but you need to check that many states in US have credits for shelter costs.