Abstract: This paper utilizes data on the records of damage to expressways and main roads caused by precipitation in Liaoning Province from 2017 to 2021. It analyzes the temporal and spatial characteristics of damage accidents, calculates the effective rainfall before the occurrence of accidents, and establishes a probability fitting model for road water damage. The results show that precipitation-induced road damage events in Liaoning Province generally occur from May to October, with a peak in July and August. The occurrence of road water damage follows a pattern of gradually delaying from northwest to southeast, and the number of accidents is highly correlated with precipitation. The eastern and western parts of Liaoning are high-incidence areas, with Dandong, Chaoyang, Huludao, and Benxi being the high-incidence areas within the province. Among various methods compared, the fitting effect of the road water damage probability conforms to the Gaussian distribution probability density function. The critical rainfall threshold for disaster in the eastern and southern parts of Liaoning is higher than that in the central and northern parts. Under the same effective rainfall conditions, the risk of road water damage in plain areas is higher than in mountainous and hilly areas. The road water damage situation during a flooding process in Liaoning in 2022 is used for verification, indicating a strong role in flood control guidance.