The number of fatal and non-fatal pedestrian injuries, due to car accidents, has increased. For this reason, design of least possible harm cars (i.e. pedestrian friendly cars) has attracted the interest of many researchers and companies in order to reduce mortality and mitigate injuries. The use of friendly cars can also lead to the reduction of the expensive medical treatment costs for pedestrian injuries and consequently alleviates the financial burdens of the governments and insurance companies. In the sedan cars accidents, the common first pedestrian body part which experiences impact is the legs. In this research, a simulation study is conducted for investigating the effects of car bumper profile and plastic grille tilt angle on the severity of collision. LS-Dyna software is used to simulate, numerically investigate and analyze the mechanism of collision between a simulated leg and a vehicle bumper. In this simulation, three parameters are considered, impact line between pedestrian leg and car bumper, the height of the bumper relative to the knee, and the plastic grille tilt angle. The results of this study showed that the increase of impact line, increase of bumper height and decrease the plastic grille tilt angle alleviate the severity of pedestrians leg injuries.