Hi I want someone to help me in this That I am transiting from Thailand. Being Pakistani Citizen will I get the transit visa upon arrival in Thailand? Also important to mention here is that I will go on Thai Airways from Beijing to Bangkok and then I ll change my flight in Bangkok and will take Bangkok to Colombo.
Assuming both flights are from the same airport (Bangkok has two international airports) and your bags are checked through to Columbo, you do not need a visa. When you disembark from your Beijing flight follow the transfer counter signs, clear security and proceed to your next gate.
If you are flying on Thai Airways for both flights, then they will likely give you both boarding passes in Beijing. But if not you can get your next boarding pass at the transfer desk.
If you are flying on two different airlines, you may need to claim and recheck bags if the two airlines don't have an interline agreement in place. In this case you will need a visa and Pakastan citizens need to apply for a visa in advance.