The invention discloses an MEMS (Micro Electro-Mechanical System) device detecting method. An MEMS device is composed of a film sheet and a back board. The method includes applying input voltage changing at a first frequency to the film sheet and the back board of the MEMS device; detecting the output voltage of the MEMS device; acquiring an electrostatic force corresponding to the output voltage according to a formula as follow; acquiring detection parameters of the MEMS device according to the electrostatic force and the output voltage. According to the invention, through applying the voltage changing continuously for simulating a real MEMS microphone, MEMS characteristics are tested, so that accuracy of the MEMS detection parameters is improved, complicated work of recording a large quantity of testing points is saved and the testing efficiency is improved.