Objective The finite element model of six-year-old children as specified in the Euro NCAP was applied to explore the mechanism of children's head injury under different collision orientations.Methods Based on the finite element model of 6-year-old pedestrian with detailed anatomical structure as specified by the Euro NCAP TB024, 4 groups of simulation experiments were set up to explore the mechanism of head injury in children under different collision angles. The initial position of the center of mass of the human head was on the longitudinal center line of the car. The car's initial speed was 40km/h. The car contacted with the model from right(0°), front(90°), left(180°) and back(270°). Results The kinematics differences and the head collision responses were investigated and the injuries of facial bone and skull were analyzed. The results indicated that the risk of head fracture and brain contusion in the condition of back collision(270°) and front collision（90°） was higher than that in the condition of side collision, among which, the risk of head fracture and brain contusion was highest in the condition of back collision（270°）, lowest in the condition of side collision（0°）, and according to the maximum principal strain of brain tissue,the risk of head AIS2+ was highest in the condition of side collision（0°）. Conclusion Through analysis, it is found that the child pedestrian head injury is the least under side collision (180°), and the mechanism of child pedestrian head injury is analyzed, which has important application value for the research and development of pedestrian - car collision protection device.