in the excavation process of 12 upper coal return air downhill roadway in Bulianta coal mine, it is faced with the threat of mine pressure near the goaf, resulting in serious slope phenomenon in the roadway and affecting the safety production of the mine. Therefore, in order to improve the overall tunneling efficiency of the roadway, firstly, the deformation monitoring of the original supporting roadway is carried out. Combined with the analysis of the monitoring data, it is concluded that the root of the roadway side support failure lies in the deep development depth of the plastic zone and the failure is caused by exceeding the effective length of the existing side bolt. The supporting length of the side bolt should be lengthened to lock its plastic failure depth in the bolt support, Then, the variation laws of plastic zone, displacement field and stress field under the two working conditions of original support and optimized support are analyzed by numerical simulation. Therefore, the optimal design scheme of return air downhill roadway side support is determined,that is, 2.6 m long bolt to replace the original design length of 1.8 m bolt , and the on-site support design and construction are carried out according to this. The roadway practice after optimized support shows that the optimized support scheme can meet the needs of field production.