The present invention provides an MEMS microphone and a method for forming the same. The method includes the following steps: a sacrificial layer is formed on a vibrating membrane, an electric conduction layer having a first opening is formed on the sacrificial layer, a side wall is formed on a sidewall of the first opening, an insulating layer is formed on the electric conduction layer, a grooveon the sacrificial layer is filled with the insulating layer so as to form an obstructing block, part of the sacrificial layer is removed, and a cavity is formed between the vibration film and the electric conduction layer. In the method for forming the MEMS microphone provided in the present invention, the side wall is formed on the sidewall of the opening in the electric conduction layer, smoothsurfaces are formed on the sidewall of the groove on which an obstructing block needs to be formed and an upper surface of the electric conduction layer via the side wall, subsequently formed obstructing block can be free from areas with poor compactness, and therefore a problem that the obstructing block can be easily eroded via an etchant can be alleviated.