Abstract: In order to investigate the influence of surrounding rock characteristics on gas drainage of through layer borehole in composite reservoir, the seepage law of gas in coal seam and rock stratum is analyzed. Based on the fluid solid coupling model of gas drainage in composite reservoir and single reservoir, the gas drainage effect of cross layer borehole with different dip angles on composite reservoir and single reservoir, and gas drainage by crossing hole coupling with multiple boreholes are simulated. The results show that the influence radius and effective radius of gas drainage from composite reservoir are larger than that of single reservoir when the same drilling hole is used to extract coal seam gas from different reservoirs; the influence range of gas drainage in composite reservoir is decreased with the increase of angle, and the influence of interlayer channeling is also weakened; under the condition of multi-borehole coupling drainage, the gas pressure of the middle and lower coal seams in the composite reservoir is obviously lower than that in the same position in the single reservoir.