从美国回国从加拿大转机：关于过境签证

不需要，新的政策已经改了，只要你有美国的签证，过境加拿大不出机场的情况下，不再需要加拿大的签证

只有温哥华可以直接转机:
http://www.delta.com/planning_reservations/plan_flight/international_travel_information/visa_passport_information/index.jsp

TWOV (Transit Without Visa):
Visa required, except for Nationals of China (People's Rep.),
(only if holding China (People's Rep.) passports) are allowed
to transit without visa via Vancouver International Airport
(YVR) to/from the U.S.A. provided:
- arriving on a direct, non-stop flight from: Beijing,
Guangzhou, Hong Kong, Shanghai, Manila or Taipei; and
- being ticketed to arrive at YVR only with the following
carriers: Cathay Pacific, China Airlines and Philippine
Airlines; and
- holding confirmed onward tickets within 24 hours of arrival;
and
- not leaving the transit area (no overnight facilities
and if transiting:
a. TO the U.S.A. passenger must hold a valid U.S. visa;
b. FROM the U.S.A. passenger must:
- be eligible for entry into the third country;
- have entered the U.S.A. on a valid visa, being lawfully
admitted and not overstayed the period of stay authorised;
- not have been deported or removed from the U.S.A., unless
being refused on a flight not cleared by U.S. pre-clearance
inspectors at YVR and within 7 days of their arrival.
Note: passengers in transit FROM the U.S.A., can depart Canada
on any airline, provided on the first leg of the journey they
were ticketed to arrive at YVR on a designated carrier
(above).

available); and
- transiting to their final destination;