The invention discloses an acceleration sensor and manufacturing method thereof. The method includes the following steps: a cavity and a first suspended film, a second suspended film and a third suspended film which are located at an upper side of the cavity, are insulated from a substrate and are in mutual insulated connection in sequence are formed in the substrate; a first electrode electrically connected with the first suspended film is formed thereon, a second electrode electrically connected with the second suspended film is formed thereon, a third electrode electrically connected with the third suspended film is formed thereon, and a fourth electrode electrically connected with the substrate is formed thereon; a torsion beam structure is formed, the first suspended film, the second suspended film and the third suspended film are connected with the substrate through the torsion beam structure, and the first suspended film and the second suspended film are symmetrical along the torsion beam structure; the first suspended film, the second suspended film and the substrate form a differential capacitance type detection structure; and the third suspended film and the substrate form a wafer level detection capacitor structure, thereby realizing a safer level self-detecting function, avoids adoption of a centrifugal machine to test, and reducing cost loss caused by a failure of an acceleration sensor.