Abstract: In this paper, the overpressure prediction model of gas explosion shock wave in the excavation roadway was established by using the theory of explosion similarity, based on the overpressure law of the explosive blast wave in the infinite space and by taking the factors such as the gas concentration, the cross-section area of the roadway, the propagation distance of shock wave and the volume of mixture into account. The relationship of the overpressure and gas concentration, the propagation distance of shock wave and the volume of the gas-air mixture was fitted according to some experiment data. The model was verified by the experiment cases, and the results showed that the model data was fairly close to that of the experiment ones.