This study investigates the stability of trial stope on the northern margin of Fengshan Copper Mine through ore rock mechanics strength tests and engineering geological surveys.The focus is on analyzing rock mass quality assessment results and calculating the hydraulic radius of the stope roof.The research findings indicate:that rock mass quality is rated as good using both the RMR method and the Q classification method;according to the Mathews stability graph method,the unsupported safe span for skarn in the northern margin ranges from 9.19 m to 11.49 m;the unsupported safe span for granite ranges from 9.45 m to 11.81 m; the unsupported safe span for granodiorite porphyry ranges from 11.40 m to 18.00 m.