In order to study the movement characteristics and risk of perilous rock collapse in mountainous highway under complex geological conditions, Anzhaiping interchange of Xinshi-Jinyang Highway was taken as an example. Field investigation, UAV aerial survey and RocPro3 D three-dimensional kinematics simulation analysis were used. Combined with the development characteristics of dangerous rock collapse and disaster damage evaluation, the protective measures of “dangerous rock removal + guide stone pile plate wall” were proposed to simulate and optimize the treatment scheme. The results show that under the influence of deep valley cutting and fault, affected by the deep valley and faults, six dangerous rock zones are developed on the slope, and four debris flow grooves are formed on the slope surface after multiple collapse disasters. After the rockfall of dangerous rock, the movement trace of rockfall along the slope surface is generally extended as “dangerous rock source area → slope → groove → slope toe”. The maximum impact energy is 1.46×10⁴ kJ, and the maximum bounce height is 32.88 m. Among them, WYD1~WYD2 rockfall trace is banded, WYD3~WYD5 rockfall trace gathers in the groove and is tree-shaped, and WYD6 rockfall trace at the ridge position is divergent. The damage to the left side of Anzhaiping No.2 Bridge is more serious than that of the right side. The maximum impact energy of rockfall is 1.05×10⁴ kJ, the maximum bounce height of rockfall is about 16.79 m, the maximum velocity of rockfall is about 42.23 m/s, and the shortest time of rockfall movement to the left side of Anzhaiping No.2 Bridge is 4.33 s. Taking 0.57 m³ as the lower limit value of dangerous rock removal of WYD6, the impact energy can be reduced by 83.87 % compared with the natural slope, and the 91 m long, 2 000 kJ anti-impact energy level of the one-shaped pile-board wall can meet the needs of rockfall interception in the working area.