A MEMS device and a manufacturing method thereof. The manufacturing method comprises: forming a CMOS circuit; and forming a MEMS module on the CMOS circuit which is coupling to the MEMS module and configured to drive the MEMS module. Forming the MEMS module comprises: forming a protective layer; forming a sacrificial layer in the protective layer; forming a first electrode on the protective layer and on the sacrificial layer so that the first electrode covers the sacrificial layer, and electrically coupling the first electrode to the CMOS circuit; forming a piezoelectric layer on the first electrode and above the sacrificial layer; forming a second electrode on the piezoelectric layer and electrically coupling the second electrode to the CMOS circuit; forming a through hole to reach the sacrificial layer; and forming a cavity by removing the sacrificial layer through the through hole.