In order to study the relationship between the driving trajectory and driving speed of small vehicles under natural driving conditions and the risky road sections of mountainous roads, the four one-way curves of Fuzhou Forest Park through the Tunxi-Guling scenic section are the research objects; The UAV is used to capture the video data of the small-vehicle-based vehicle from the curve to the exiting natural driving process, and the tracking motion module of the Ae software is used to track the trajectory of the left front wheel of the vehicle and calculate the vehicle turning speed; The length of each curve risk section is obtained according to the driving trajectory and the traveling speed. The results show that the risk section of curve 1 is 0~2.273m and 32.838~39.268m, the risk section of curve 2 is 43.375~46.039m, the risk section of curve 3 is 21.001~21.507m, and the risk section of curve 4 is 18.521~24.283. In this study, the two actual driving data of vehicle trajectory and driving speed are used as the entry point, which provides a method based on the natural driving state of small vehicles for the identification of risky road sections in mountainous areas.