Abstract: It is difficult to obtain the information of damage area, underground person distribution, the best rescue line and so on after a gas explosion in coal mine. To solve the problem, an assistant decision system of gas explosion emergency rescue was designed based on real time monitoring data and computational fluid dynamics (CFD) numerical simulation. First of all, the access technology and management technology of the real-time monitoring data, used in the gas explosion simulation and emergency rescue decision, were studied. Secondly, some laws were made to trigger the gas explosion numerical simulation automatically by calling the FLUENT software. And then, the equivalent length for rescue of tunnel after explosion was counted by equivalent length method to select the optimal rescue route. Finally, the assistant decision system was implemented based on 3D visualization platform, and installed at demonstration coal mine.