Abstract: The relevant standards of explosion-proof diesel engine, the maximum safety gap and the using status are described in this paper. The paper analyzed the structure of typical barrier plate type flame arrester, established mathematical model of gas transport by pressure loss theory, designed physical model of pressure loss of fire arrester, and then used large-scale fluid dynamics software Fluent to carry out numerical simulation. Taking the average pressure difference of front and rear tubes as standard of pressure loss, pressure loss of fire arrester of different parallel plate clearance is simulated, and pressure loss is analyzed by the explosion-proof grille internal velocity vector and turbulence energy cloud. On the basis of two adjacent fence board clearance of flame arrester with 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm and 1.2 mm, the flame-proof performance was tested. The maximum safety clearance of the specific condition of flame arrester of explosion-proof diesel engine was obtained.