Abstract: In order to study the optimal proportion of double filling wall along goaf retaining wall and its influence on roof gas leakage of working face, Taking the 2603 working face of Zhangcun Coal Mine as the engineering background, By preparing cubic composite samples with different proportions of concrete and high water material, the optimal proportions were selected from the study of mechanical properties and macroscopic fracture forms of the composite samples with different proportions,and based on the characteristics that the upper soft layer can fully connect the roof and prevent the upper gas leakage, the gas concentration of the roadway is monitored.The results show that when the proportion of high water material is 10%, 20%, 30%, 40% and 50%, the peak strength of the concrete decreases by 18.95%, 44.23%, 52.31%, 60.78% and 79.68%, respectively, compared with the peak strength of pure concrete. When the proportion of high water material is less than 20%, the combined specimen has the effect of letting pressure while ensuring a certain strength.When the proportion of high water material is more than 20%, the high proportion of soft stratified material will reduce the supporting effect of high strength material at the bottom, thus affecting the overall strength of the specimen. The application results show that the gas concentration can be effectively reduced and the effect of roadway retention is good.