回複：F1從加拿大旅遊回美國,還要簽證嗎？

If you travel to Canada and stay there for less than 30 days ( I am pretty sure), you don't have to get another visa when you come back to US. But, before you trip, you need to get a signature from your International Advisor on your current I-20, then bring your passport with I-94 and your I-20. If you've ever transfer school, you'd better bring all of your I-20s.

Good luck!