Four mathematical models were developed to represent 3-, 6-, 9-, and 15-year-old child pedestrians. In the absence of biomechanical data of children, resistive properties of various joints and body segments were scaled down from that of a validated adult model. Differences in anatomical structure and age-dependent properties of biological tissues were taken into consideration. In this study, the primary effort was emphasized on the scaling of lateral bending properties of the vertebrae column and knee joint, as well as the contact stiffness of the lower extremity. The scaling factors of contact stiffness for other body regions, such as head and thorax, were adopted from the literature. To evaluate the performance of the child pedestrian models, two real-world accidents were reconstructed by using the accident data from in-depth investigation. The impact responses of child models agreed reasonably well with the actual injury outcomes in accidents.