Abstract: A 3-D dynamic mathematical model of gas explosion flow field was built based on explosion mechanics, explosion dynamic mechanics and thermodynamics. The way of boundary conditions defining was studied by experiment and theory analysis, and the total variation diminishing (TVD) was used to numerically solve the mathematical model. Numerical simulation results show that barricade excitation will be formed in combustion and other areas while the pressure is increased to detonation, and the fields of pressure and velocity around the barricade is greatly changed in the whole area of explosion.