Abstract: In order to get the reasonable position of the high hole in the top plate of the composite mining roof，using the 2601 working face of a certain mine as the engineering background，the numerical calculation software UDEC was used to simulate the mining of the top coal，and the expansion and deformation evolution laws during the movement of the top plate rock formation were obtained.Based on the above laws,it is determined that the top plate high drilling arrangement is located in the range of 17~22 m above the top plate of the 2601 working face.The field verification shows that the gas extraction concentration is high and the flow is stable.

Key words: Reasonable level, Expansion and deformation, High drilling, Concentration, Flow