Abstract: In order to further study the influence of key blocks on the stability of roadway surrounding rock and design support measures through key block analysis. Taking an underground mining roadway in Mengku Iron Mine as the research object, through engineering geological survey and field testing, statistics and segmentation of surrounding rock joints and cracks are carried out, rock block strength test and wave velocity test of rock mass are carried out, rock mass integrity parameters are obtained, and detailed engineering classification of rock mass is carried out according to this, and mechanical classification parameters of different rock masses are given. Then, the key block analysis is carried out through Unwedge, the unstable rock block is defined, and the stability analysis is carried out, and the supporting parameters and key supporting positions of the anchoring and spraying are determined. Then the finite element software is used to simulate the excavation process and analyze the changes in the stress and strain of the surrounding rock during the excavation process, and the in-situ mining stress is monitored and analyzed. The research results show that through the analysis of key blocks, the unstable rock blocks that may lead to roadway instability can be identified more accurately. Based on the analysis results, the stability improvement measures are proposed and applied to the field for mining stress monitoring and analysis, and good results are obtained. The research results provide a reliable basis for the stability analysis of surrounding rock and support design to some extent.