The present disclosure provides a film thickness test apparatus and method, and a vapor deposition device. The film thickness test apparatus is arranged for one process cavity, and the film thickness test apparatus comprises: a test assembly; a transport assembly configured to, when moving towards the process cavity, drive the test assembly into the process cavity so that the test assembly is vapor deposited in the process cavity to form a test film, and, when moving away from the process cavity, drive the test assembly out of the process cavity; and a drive assembly configured to drive the transport assembly to move along a direction towards/away from the process cavity.