Exploitation of the shale gas in Changning area, Sichuan Province, is companied by numerous earthquakes including several moderate ones, and the seismic risk is increasing. With 241225 earthquakes detected, by a deep learning method, from the continuous records between May 2021 and June 2022 by a dense seismic array consisting of 107 stations in Changning area, we have estimated the b
value in the frequency-magnitude relationship and analyzed its spatiotemporal characteristics. The b
value for the whole area is 1.06; it is 1.25 and 1.01 for Changning-Shuanghe salt mining region and Changning-Zhaotong shale gas region, respectively. The low b
value indicates that stress level in the shale gas region is higher. The b
value remarkably varies in space and its variations are probably relative to the heterogeneity of the subsurface media. Basically, big earthquakes lie in low b-
value regions, and the b
-value appears low or drops before such events’ occurrence.