US Permanent Residents no longer need to apply eTA for transit in Canada, effective April 26, 2022.
2022年4月26日起，美国公民和美国绿卡持有者不需要申请eTA入境或过境加拿大。

No need to apply visa or eTA to transit in Canada.
不需要签证或eTA过境加拿大

China citizens with valid US visa may be qualified for China Transit Program (CTP), limited to Vancouver and Toronto Terminal 1, Air Canada, Rouge, Jazz, Cathay Pacific, Air China, China Airlines, China Eastern, China Southern, Hainan Airlines, Philippines Airlines, Xiamen Airlines, WestJet operated flights. Codeshare flights operated by other airlines such as United are not eligible.
If you meet above criteria, you do not need to have an eTA or a visa to transit Canada.
中国公民在上述机场过境并且乘坐上述航司则免签证和eTA
Need to apply visa if your operating airline is not listed above.
如您的航班执飞航司不在上面，则需要申请签证方可过境加拿大。

Visa needed countries 需要签证国家名单

Visa exempt countries 免签证国家名单
Visa-exempted country nationals need to apply eTA
免签证国家公民需要申请 eTA
Apply eTA

Taiwan/Thailand/Philippines/Indonesia citizens with valid US visa may be qualified for Transit Without Visa (TWOV), limited to Vancouver and Toronto Terminal 1, Air Canada, Rouge, Jazz, Cathay Pacific, Air China, China Airlines, China Eastern, China Southern, Hainan Airlines, Philippines Airlines, Xiamen Airlines, WestJet operated flights. Codeshare flights operated by other airlines such as United are not eligible.
Participants in the Transit Without Visa (TWOV) Program, do not need to have an eTA or a visa to transit Canada.
台湾、泰国、菲律宾、印尼公民在上述机场过境并且乘坐上述航司则免签证和eTA。