China is one of the most storm surge-prone countries in the world. Estimation of the inundation caused by the probable maximum storm surge (PMSS) is an important facet in the design of key structures (such as coastal nuclear plants) and provides a scientific basis for the planning of storm surge mitigation schemes. In this study, we propose a method for calculating the range and depth of inundation caused by PMSS based on a numerical storm surge model together with data from historical records. The proposed method was validated via a case study of the Fengxian District of Shanghai. Specifically, we defined typhoon intensity, radius of maximum winds, typhoon track, and astronomical high tides related to probable maximum tropical cyclones, based on historical data, to describe the set of typhoon events that could result in the PMSS in the Fengxian District. A high-precision numerical storm surge model of the study area was constructed to simulate the PMSS-induced inundation of the study area. The results of our simulation indicate that the Fengxian District would be severely affected by PMSS-induced flooding and the maximum depth of inundation would exceed 3 m. The proposed method can be applied across various coastal counties, serving as an effective tool for decision making related to storm surge risk reduction practices.