A method for determining a peak position of lower extremity injury in a crash test dummy includes: controlling the movement of the collision surface until the control point of the collision surface and the first designated collision point of the dummy's lower extremity form a line parallel to the direction of the vehicle acceleration, with a predetermined distance between the control point and the first designated collision point. A collision simulation calculation is performed to obtain the first tibial index curve, the first knee displacement curve, and the first thigh force curve. Similarly, the second designated collision point is used to obtain the second tibial index curve, the second knee displacement curve, and the second thigh force curve. Then, the injury values are calculated, and by comparing the injury values at different positions, the peak position is determined.