Based on the three-dimensional numerical model of drainage system, the influences of different upstream and downstream pipe diameter ratios and relative heights, chamber and shaft parameters on geyser pressure and intensity were analyzed. The results show that smaller relative height of the upstream and downstream pipes can cause the flow regime in the upstream pipe to be full pipe flow, and the rapid increase in upstream flow can induce greater geyser pressure. Reducing the diameter of the downstream pipe can reduce the transport capacity, resulting in more severe geyser. When the chamber volume is constant, increasing the chamber height can alleviate the maximum geyser pressure. Increasing the shaft length has little effect on the geyser pressure, but it can reduce the volume of water ejected. Increasing the shaft diameter makes the geyser pressure to increase first and then decrease.