Abstract: A novel low power consumption portable methane instrument is designed, which uses the MEMS catalytic methane detector as the main sensitive component, and uses pulse supply to reduce power consumption. In this paper, the overall design scheme, primary circuit and the most important algorithm is described. The test results show that the designed portable instrument has high precision, low power consumption, long working time, and can fully meet the requirements of underground workers in coal mine for monitoring the ambient methane concentration.