Abstract: A foam nickel iron metal could have a function to isolate the gas explosion，in order to study the obstacles existed in the underground mine affected to the inhibited gas explosion effect of the foam nickel iron metal,a mine gas and coal dust explosion system was applied to the inhibition comparison tests on one layer,three layers and five layers obstacles individually with a blocking rate of 15%,25% and 40%. The test results showed that after the obstacles placed,the foam iron nickel metal could reduce the overpressure of the gas explosion and the flame speed inhibited function in the pipeline. The inhibition function of the gas explosion overpressure was obviously reduced. When the five layers obstacles with the blocking rate of 25% and the five layers obstacles with the blocking rate of 40% were placed,the foam iron nickel metal lost the inhibition function of the gas explosion overpressure in the pipeline. The blocking rate and the layers of the obstacles were the two factors affected to the inhibited gas explosion effect of the foam iron nickel metal. The product of the blocking rate and the layers were defined as the limit affected to the obstacles. When the influence limit of the obstacles reached at 125% or above,the foam iron nickel metal would lose the inhibition function of the gas explosion overpressure in the pipeline.