In response to the issue of flood resource utilization of the Feilaixia Reservoir, a river-type reservoir in the Beijiang River Basin, a reservoir flood control operation model was constructed based on the principle of efficient utilization of water resources in river-type reservoirs with multiple constraints. Based on the decision tree method, the variation law of the available amount of flood resources under two optimization scheduling schemes of accelerating re-storage in end of flood season and raising normal water storage level was analyzed. The stochastic flood process method was used to simulate and calculate the risk probability of flood resource utilization under both schemes. The results show that raising normal storage level of Feilaixia Reservoir to 24.8 meters is a recommended solution with a small marginal increase in risk, which can increase the annual water resource utilization by 646 million cubic meters and has a significant effect on alleviating water supply shortages.