Abstract: In order to analyze the safety of the anti-backflow device for the ventiduct in the coal and gas outburst accident, the existing anti-backflow device was studied, and the dynamic characteristics of the existing anti-backflow device under the effect of the outburst shock wave overpressure of 10MPa coal seam gas pressure, basing the research results and safety design concepts Give an improvement plan. Combined with fluid dynamics, the mathematical model of shock wave overpressure at different positions of the roadway is obtained. According to the corresponding regulations and actual safety requirements of the coal industry, the LS-DYNA software is used to numerically simulate the structural damage of the blower backflow prevention device under the impact load. Obtain the dynamic characteristics of the anti-backflow device of steel wind tube of different structure and material. Research shows that the cross-sectional area of the ventiduct is much smaller than the cross-sectional area of the roadway. Due to the reduction of the cross-sectional area of the propagation path, the overpressure of the shock wave entering the ventiduct from the roadway will suddenly increase to five times that in the roadway. The maximum stress of the existing anti-backflow device under the shock wave overpressure of 10MPa coal seam gas pressure scale reaches 664MPa, which is far greater than the yield limit of Q235 steel of 235MPa,which cannot meet the safety requirements; The maximum stress of he improved structure of the 25mm and 30mm thickness anti-backflow device under the worst conditions is less than the yield stress of the material, and the maximum displacement is much less than its own thickness, which can meet safety requirements and the improvement plan is reasonable.