Abstract: In order to recognize the removing outburst effect of the borehole pressure relief and gas drainage of large diameter hole along the seam in a microscopic view,numerical simulation was studied on 17171(1)working face in Pansan Coal mine by the RFPA^2D-Flow code.According to the numerical simulation,if the hole diameter increased 2 times,the displacement of coal above the hole increased 8.4 times,and gas flow around the hole increased 1.37 times;when the hole spacing was 2 meters,the gas drainage was effective from the coal between the two holes,maximum permeability coefficient of coal increased 250 times.According to the fieldwork experimentation,after adopting the large diameter hole along the seam technology,the test results of removing outburst region in haulage gate and tail entry met regulatory requirements,and forecast the heading face outburst risk 55 times,no indicators overrun.It proves that in the condition of lacking protective seam,the large diameter hole along the seam has significant effect to remove outburst of seam.