Abstract: in order to detemine the rational space between the boreholes for gas drainage with the boreholes in and along the sean in coal mine,based on the actualsean deposition condions,a pressure drop method was appid to experiment studly on the gas drainage radius ofthe borehole.A 3D gas rainage borehole modelwas esteb ished by Cconsol Aultihy scs numeical sinuation software. Acording to the simulation resuls of a single borehol ,the vaiation laws of gas drainage effectve radius r and gas drainage infuence radius R of the borehole were obtained, and the varation law was highly met with the actual measured resuis of he pressure drop method.Therelailty of the3 D model was verfied. ith the analysis on the gas fiow state around the borehole and the funcion mechanism of the gas superpositionefec.the paper had a simulaton stuly on the gas drainage ef ct under diferent space between the boreholes.The rational space between the boreholes for gas drainage along the seam was 2r LSR.n the acual gas drainage operaton.according to the mining and excavation schedule of mine the rational space between boreholes could be set up and the mine safety production would be ensured while the drainage cost was reduced.