The underground rock conditions of a copper nickel mine are poor. In the early stage, the collapse mining method was used to recover mining stone resources,. Due to the long exposure time of the collapse mining site and the influence of mining disturbance, the mining area experienced roof collapse and side slope collapse before treatment, resulting in weakened mining technology conditions for the upper rock and making it impossible to safely extract over a million tons of ore resources under the current situation. Based on this, a detection method combining TRT advanced detection and geological drilling was adopted. The loose boundary roof elevation of the mining area affected by the bottom pillar collapse method was detected to be 760m level, the upper wall boundary was approximately vertical, and the lower wall boundary was inferred based on a rock movement angle of 60 °. The loose boundary roof elevation of the mining area affected by the non bottom pillar collapse method was 755m level, and the situation of the upper and lower walls was similar to that of the mining area affected by the bottom pillar collapse method.The detection results can provide a basis for the selection of mining methods, mining preparation engineering layout, support methods and their strength application for the ore resources in the area, ensuring safe and efficient underground production.