The steep incline and fractured ore-bodies in Yongshaba mine belong to the category of difficult-to-mine ore-bodies. They are extremely fractured, leading to a lot of problems in the actual production. Such as, the in-vein drill drifts are difficult to support and the working environment is dangerous. After studies of the ore-body conditions, it is decided to adopt the method of reconstructing the manual roof and filling the downward sublevel stagger based on the pre-design sublevel rock drilling stage vacant stope backfill mining method. A reinforced concrete sub-top is reconstructed on the stope, staggered arranging the stope and the up and down sublevel pillars are built to support the upper ore-body, so the workers can work under the protection of the sub-top. Due to the increased sublevel's height, the drilling efficiency is further improved, and the stope production capacity is guaranteed. The mine can have safe and efficient productions. The improvement method is applied successfully in the mine.