The source parameters of 442 earthquakes from December 2018 to July 2019 in Changning area of Sichuan Province are calculated by spectral ratio method,and the relationship between the source parameters and the spatiotemporal distribution characteristics of stress drop are analyzed. The earthquakes in the study area are mainly concentrated in the Changning M_S6.0 earthquake source area at the core of the Changning anticline and the Jianwu syncline shale gas mining area. We find that the stress drop of earthquakes with M_L1.3~4.7 is in the range of 0.02~7.26MPa, more than 90% of the earthquake stress drop is less than 2MPa,and the stress drop increases with the magnitude,but the relationship with the focal depth is not obvious. Before the occurrence of the Changning M_S6.0 earthquake,the stress drop of earthquakes in this area was generally at a low level. After the occurrence of the main earthquake,the stress drops of aftershocks increased significantly,and then decreased rapidly. In spatial distribution,the earthquakes with high stress drop are mainly concentrated in the northwest of Changning anticline,where several M_S>5.0 aftershocks have occurred. While the stress drop of earthquakes in Jianwu syncline is relatively low. The stress drops of earthquakes in the Jianwu syncline shale gas mining area is slightly lower than that of the Changning anticline area,but the difference is not significant.