A multi-floor type MEMS microphone includes a housing formed by a stack of circuit boards and provided with a first cavity, a second cavity in vertical communication with the first cavity, and a sound hole in communication with the second cavity. The second cavity has a vertical cross-sectional area smaller than that of the first cavity. A MEMS transducer is disposed in the second cavity and electrically conducted with the housing, and an ASIC chip is disposed in the first cavity and electrically conducted with the housing. By this design, the volume of the back chamber of a vibrating diaphragm of the MEMS transducer can be increased in a limited space of the housing, and thus the sensitivity of the microphone can be improved.