The present invention provides a piezoelectric MEMS microphone having a base with a cavity, a piezoelectric diaphragm, and a restraining element. The base has a ring base circumferentially forming a cavity, a support column. The piezoelectric diaphragm includes diaphragm sheets each having a fixing end connected to a support column and a free end suspended over the cavity. The restraining element has one end fixedly connected to the free end, the other end connected to the part on the base that is not connected to the fixing end. The piezoelectric MEMS microphone of the invention can constrain the deformation of the diaphragm sheet, thereby improving the resonant frequency of the piezoelectric diaphragm, reducing the noise of the whole piezoelectric MEMS microphone.