In order to achieve the safe mining of unequal length working face, continuous, real time and dynamic microseismic monitoring research was carried out at No.15240 face of Fengfeng Group Jiulong Mine. The results showed that the microseismic response of unequal length working face had periodic characteristics, which could be divided into three development stages: narrow face, narrow to wide and wide face. In the stage from narrow to wide, the frequency of microseismic events increased significantly, the energy increased greatly, and the stress concentration appeared. After the working face became wide, the increase of floor events was greater than that of roof events, and the average floor disturbance depth increased.