Answered by ZUPAN | Nov. 23, 2019 08:00
No, you don't. Your itinerary is definitely eligible for 24 hour visa free transit and you don't need any kind of visa.
You will print out your flight tickets and have those printouts with you. Also, you will declare at check-in in Kathmandu that you will travel to US via Guangzhou using 24 hour visa free transit. After a short inspection of your tickets, you will be allowed to board the plane. Also, during the check-in procedure, you will ask whether your luggage will be tagged all the way to US, so that you know what will you have to do regarding this detail. It will be almost certainly tagged all the way to US, but you should ask, just for a case.
Upon your arrival in Guangzhou, you will just accomplish several formalities like shortened version of immigration control and security and after that you will proceed to your boarding gate for your flight to US.