Does Air Canada require a Canadian transit visa when transferring from Vancouver to San Francisco?

If you are transiting from Canada to the United States without going through Canadian customs, you can be conditionally exempted from the visa; if you want to go out of Canadian customs, you need a Canadian visa. Furthermore, a U.S. entry visa is required for transit in the United States. Since Canada has long opened the multi-entry tourist visa for Chinese citizens with a maximum validity period of passport (ten years), and with the opening of the ten-year multi-entry tourist visa to China, now you only need to apply once and you can often Get Canadian and US visas with valid passports.

The visa requirements for transiting from Canada to the United States are detailed:

If you do not have a Canadian visa, you can also transit from Canada to the United States because the Canada Border Services Agency (CBSA) and Immigration Services (CIC) has jointly established the China Transit Program (CTP) for Chinese citizens to transit through Canada without a visa. This project allows citizens of the People's Republic of China to exempt themselves from Canadian transit visas and transit to/from the United States via Canada when all of the following conditions are met:

Possess a valid Chinese passport.

Possess a valid U.S. visa.

Flights with the following airlines: Air Canada; Jazz Aviation LP; Cathay Pacific; China Airlines; Philippine Airlines ); Air China.

Transit through the following approved airports: Vancouver International Airport, Canada; Toronto Lester B. Pearson International Airport, Terminal 1 only.

If you are going to the United States, you must depart from the following cities and take direct flights to Canada: Beijing; Shanghai; Guangzhou; Hong Kong; Manila; Taipei.

Must hold a valid connecting ticket to/from the United States on the same day.

You must enter the U.S. Customs during business hours and cannot stay or stay overnight in Canada: Toronto 04:30-21:00; Vancouver 04:30-20:30.