In order to study the propagation law of gas explosion flame in underground bifurcation tunnel of coal mine, a bifurcation pipeline experiment device with bifurcation angle of 45° was made, the gas explosion experiment with methane concentration of 9.5% was carried out and Fluent 16.0 software was used to simulate the propagation process of gas explosion flame in the bifurcated pipeline. Experimental data were compared with the simulation results to analyze the variation law of the gas explosion flame propagation. The results show that:1) The gas explosion flame in the bifurcated pipeline generates vortex at the bifurcation, accelerating the turbulence of the explosion flame in the pipeline, and the shock reflection of the flame is obvious. 2) Explosion flame temperature, propagation speed, shock wave overpressure and ionic current at the section of bifurcated branch pipe reach their peaks. 3) There are some value differences between the simulation and the experiment results, but the overall change law of gas explosion flame propagation is the same. The research results provide certain references for understanding the mechanism of underground gas explosion propagation and formulating measures to suppress it at the bifurcation of roadway in the coal mine.