Abstract: In response to the varying standards for the construction of drainage systems in large airports, which makes it difficult to predict the risk of airport flooding, a comprehensive assessment of flood prevention and control capabilities was conducted using Beijing Capital International Airport as the research object. SWMM model was used to simulate the drainage process of the airport under different return periods of design rainstorm, and the key risk points were identified. The results show that the airport drainage system can basically ensure the normal operation of the airport under the return period of 5 years of rainstorm; Under the rainstorm with return period of 10 years and 20 years, the number of drainage restricted pipe sections and overflow nodes increased significantly, and some aprons and taxiways were affected; Under the rainstorm with a return period of 50 years, the drainage restriction was further aggravated, and the drainage capacity of several pipe sections reached the limit. In addition, the model also revealed that the chain reaction between interconnected pipe sections has a significant impact on drainage capacity. Based on simulation results, optimization strategies for flood control and protection capabilities under different recurrence periods of heavy rainfall were proposed, including the installation of water blocking components for key facilities and the implementation of diversion and improvement procedures for flooded road sections.