The invention discloses a micro accelerometer with an FBAR structure on a diaphragm, comprising an inertial force sensitive structure, a detection element and a composite film, the composite film is used to connect the inertial force sensitive structure and the detection element, the inertial force sensitive structure is located below the composite film, and the detection The element is located above the composite film; the inertial force sensitive structure includes a Si mass block, a Si base and a cavity; the Si mass block is arranged in the central area of the bottom of the composite film, and the Si base is arranged in a ring shape at the edge area of the bottom of the composite film. There is a cavity between the Si mass, the Si base and the composite film, that is, the Si base surrounds the Si mass, the Si mass and the Si base are separated by the cavity, and the corresponding composite film on the Si mass and the cavity is The elastic diaphragm area; the detection element includes FBAR, leads, and pads, and the FBAR is connected to the pads through leads; the invention has the advantages of good manufacturability, high temperature stability, small cross-coupling between modes, and high mechanical strength.