Abstract: In order to find out dynamic variation law of coal powder output during coalbed methane drainage, the coal powder output was recorded and counted dur ing the drainage of coalbed mathane in the south of Qinshui Basin. In addition, the influence factors of coal powder output were analyzed, and the relationship between coal powder output and gas production was studied based on cases. The results showed that water drainage stage and gas-water two-phase stage were the most likely coal powder output stage, of which the coal powder output during gas-water two-phase stage was generally high, and instability and discontinuous were main variation characteristic. The main influence factors on coal powder output were the characteristics of fractures, configuration relations between tectonic soft coal areas and fractu res, carrying coal powder capacity of formation fluid, as well as drainage system. It was benefit to decrease coal powder to damage the coalbed mathane drainage whe n strengthening coal reservoir geological study, avoiding primary coal powder, developing the portable detector to test coal powder content, formulating coal powder pre -warning measures, and optimizing drainage working system.