Abstract: By means of similar simulation experiment, field measurement and theoretical calculation, the parameters of high level gas drainage borehole in 11B801 fully mechanized top coal caving face of Tahe coal mine are studied. The results show that there is a "large and small period" pressure phenomenon in the recovery process of 11B801 fully mechanized caving face. The small cycle average pressure step distance is about 15.5m, and the large period average pressure step distance is about 65.0m. The "large and small period" is closely related to the development of gas migration channel and the development of the gathering place. Based on the "big and small cycle", the effective length of the high borehole is determined, and the parameters such as depth, elevation and stubble distance are calculated. Through the analysis of the monitoring data of roof pressure and drilling extraction concentration during the working face recovery, the reasonableness of calculating the drilling parameters with the backstepping of the step distance of the "large and small period" was verified. The gas control of the upper corner of the 11B801 fully mechanized caving face was below 0.47%, which ensured the safe and efficient production of the 11B801 fully mechanized caving face.