The invention provides a protection structure for vehicles and a design method thereof and relates to the field of vehicle components. The protection structure is located at the front end of the vehicle and is used to protect the tibias and knees of a pedestrian's calf in the event of a collision between the vehicle and the pedestrian; the protection structure comprises a support body whose surface is provided with multiple first reinforcing ribs; a plurality of the first reinforcing ribs are configured to be arranged from one end of the support body along the length direction of the surface of the bracket body to the other end of the support body; adjacent two first reinforcing ribs are arranged crosswise so that the support body does not generate a local bending moment when the collisionoccurs, thereby protecting the calf shank of the pedestrian; the surface is the largest surface area of the support body. The invention solves the dangerous problems of fracture of lower tibia and knee of calf caused by collision between vehicle and pedestrian due to unreasonable protection structures in the prior art.