Abstract: Under the condition of IV-level broken marble roof of ZnV3 ore body in a lead-zinc mine， when the two-step stoping method of stage open stoping with subsequent filling is applied，the problems such as roof and side collapse exposed in the I-step stope and unreasonable mining preparation project pose challenges to the safe stoping in the II-step stope. Therefore，the systematic optimization design of the II�step stope is carried out. The key points of optimization include stope structure parameters，mining prepara‐ tion engineering layout，roof and side support scheme and blasting and ore falling process. Through industri‐ al test verification，the optimized mining method significantly improves the stability and operation safety of the stope roof，and effectively controls the ore dilution loss rate within 15%.This optimization scheme effec‐ tively solves the problem of safe and efficient mining of the II-step stope under the condition of broken roof, and has the value of popularization and application in similar mine.

Key words: gently inclined thick ore body, broken roof, stage open stoping with subsequent filling, mining process optimization