Objective To evaluate the harmfulness of micro-miniature unmanned aerial vehicles (UAV) to human body, especially to head caused by accidental uncontrolled crash. Methods The dynamic numerical simulation analysis was carried out by using ABAQUS software. The free-falling UAV was simplified in different geometric shapes to impact human head and the damage degree of human head caused by the impact was analyzed. Based on the biological tissue performance parameters, human head and neck was simplified as a mass-spring system and the head was modeled with actual skin texture. Results When the UAV fell from 10 m with weight of 0.5 kg, the abbreviated injury scale (AIS) of the disc-shaped UAV was 1.04, and the AIS of the corn-shaped and sphere-shaped UVA were 1.95 and 2.48. For the UAV with the same geometric shape, as the mass and the falling height increased, both impact acceleration of the head and the AIS increased. When the UAV impacted human head at different angles, the disc-shaped UAV exhibited the smallest impact acceleration, AIS and damage degree. The corn-shaped and sphere-shaped UVAs had small differences in impact acceleration and AIS, but their damage degrees were large. Conclusions When the uncontrolled micro-miniature UAV impacts human head, the mass, height or contact shape of the UAV have a significant influence on the damage degree of human head.