Abstract: The VO2 microbolometer has been prepared by micro electrical mechanical system（MEMS） bulk-silicon process for infrared gas detection.The emphasis is placed on the researches of the preparation process.By optimizing the process parameters,the prepared microbolometer behaves steady structure and high yield.The characterization of the device is also tested.The results show that when the light modulation frequency is 1Hz,the responsibility is ~18.1kV/W,the detectivity is about 1.37×10⁸cmHz^1/2/W,and the thermal time constant is ~72.4ms.