To reveal the laws about gas under the condition of strong detonation and weak detonation shock wave overpressure changing,with one-dimension explosion physical model and the theory, the mathematical model of shock wave overpressure changing with distance was set up. With a change of ignition energy and gas concentration of unchanged in the pipe, the gas detonation was achieved and the theory solution was verified in semi-enclosed space. Results show that the strong shock wave overpressure change is inversely proportional to the propagation distance, very weak shock wave overpressure and the propagation distance is inversely proportional to the square root of. Under the condition of deflagration flame propagation speed is much less than the detonation under the conditions of flame propagation speed. Detonation and deflagration of the theoretical solution is less than the experimental value, but the whole transmission trends are basically identical. Value theory solution agreed with the experimental values. The research results provide technical support and theoretical guidance for the prevention and control of gas explosion accident.