Rockfalls on debris slopes are a major hazard for Canyon roads on the Tibetan Plateau. For risk assessment and engineering treatment, it is crucial to fully understand the movement characteristics and process of rockfalls. In this research, the UAV and three-dimensional (3D) laser scanner are employed to obtain images and data, Pix4D is employed to build the collected data into a high-precision 3D model. Unity3D is used to study the movement characteristics and deposit position of rockfalls, the movement characteristic indexes are computed and examined, for blocks with various shapes, sizes, and instability types on the debris slope and blocks with different slope materials and inclination, such as velocity, acceleration, displacement, energy loss, and deposit position, the movement mechanism of debris slope that differs from the common slope is obtained. The effectiveness of the Unity3D simulation approach was confirmed by field experiments. On this basis, Unity3D was used to establish a high-precision 3D simulation model for the debris slope of the G318 road on the Tibetan Plateau and to compute the movement characteristics, energy variation, and deposited position of rockfall. Then, the findings are compared with those of common models. This shows that the results of the high precision 3D simulation model computed by Unity3D are more accurate and reasonable than the common model, and the movement characteristics, energy variation, and deposited position of rockfall on debris slopes are characterized by specificity. Thus, the phenomenon and behavior of rockfall on debris slopes can be completely realized using Unity3D simulation analysis, to propose more reasonable engineering protection countermeasures.