Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 12:55 and arrives at Shenzhen Shenzhen Bao'an International Airport at 17:00.
The flighttime is about 3h 05m. The distance travelled ("as the bird flies"): 1477 Km. So the average speed is roughly 479 Km.
There is an 1 hour time difference between Bangkok and Shenzhen