Abstract: A mathematical model, considering the inner and outer fields of explosion vessels, was introduced to explore the induced mechanism of high explosion-vented pressures and the characteristics of flame and pressure transmission in spherical vessels. Based on the conversation equations for hydrodynamics and chemical reaction dynamics, by adopting the k-e turbulent model and the EBU-Arrhenius combustion model, the SIMPLE algorithm was used to investigate numerically the methane-air premixed gas vented explosion process in the two-dimensional space of the spherical vessel with a conduit for explosion venting. The characteristics of flame and pressure transmission and gas flow in the process of vented explosion were obtained which could reflect the dynamics of gas explosion. The turbulent combustion appearing in the process of vented explosion accelerates the transmission of the combustion flame. Venting explosion conduits confines seriously the high-pressure gas venting from vessels.