Abstract: Impact damage caused by fishing vessel trawling poses a great threat to the safety of subsea pipelines,and the impact risk assessment of trawl plates is an important part of subsea pipeline protection design,which usually involves the estimation of impact frequency and corresponding damage degree.Although DNV provides recommended practices for calculating impact frequency and impact energy,there is still a lack of methods to take into account vessel traffic and fishing vessel trawling information in different regions.Based on the AIS data in the South China Sea,the trawl trajectories of fishing vessels were identified,the trawl trajectories were compressed and clustered by Douglas-Peucker algorithm and DBSCAN algorithm,the impact frequency of trawl board on subsea pipeline was calculated,the pipeline damage degree caused by each impact was analyzed by risk matrix,and the risk assessment of subsea pipelines by impacts of trawl board considering impact frequency and damage degree was realized.The method proposed in this paper can help to improve the risk assessment and protection design of subsea pipelines.