Based on the drift flow mathematical model, the heat transfer tube system with a surge tank was simulated, and the heat transfer characteristics under different heating powers, inlet fluid temperatures and mass flows conditions were analyzed. It is found that the rate of change of gas velocity is larger than that of liquid phase with changing initial parameters. With the increase of heating power and inlet fluid temperature or the decrease of mass flow, the total pressure drop increases. Comparing the heat transfer tube with a surge tank and without surge tank, and by analyzing the response of pressure drop, quality and other parameters to step changes of the system with a surge tank was found to require less time to reach stability and less amplitude.This shows that the surge tank can reduce the risk of frequent changes in load of system.