Climate change and rapid urbanization development in the western region of the Taihu Lake Basin, China, would change the precipitation and its variability, which are often related to water disasters. Under these circumstances, the need for accurate information about extreme rainfall events has been amplified. Based on the daily rainfall data of Danyang, Jintan, Liyang, and Yixing rainfall stations from 1961 to 2015, the annual maximum daily rainfall under different return periods was analyzed using the principle of maximum entropy (POME) method. The results show that annual maximum daily rainfall of more than 50 mm happened nearly every year at each station. When the return period was 100 years, the maximum rainfall at Danyang and Jintan was 269.51 mm and 261.68 mm, respectively, reaching the level for heavy rainstorms. We hope this study could provide a scientific reference for prevention and risk management of extreme climate in the western region of the Taihu Lake Basin.