The invention provides a method, a device and a system for testing a function of an air conditioning controller. The method comprises the following steps that: a test device sends a test command to a test board; the test board simulates air conditioning running working condition data to obtain simulation data; the test board sends the simulation data to a tested controller; the test board detects the tested controller and sends detection data to the test device; and the test device judges whether the function of the tested controller is normal according to the detection data. By the invention, the function of the air conditioning controller can be detected automatically, so that the detection speed can be increased.