To supply comprehensive protection for children with variable shapes and sizes, impact injury of obese children was studied based on 10-year-old finite element model. In this paper, the WSU 10-YO FE model was varied using mesh morphing methodology with specific geometries defined by the body surface which can be acquired by the combination of pediatric anthropometric database and generator of body (GEBOD). The obtained FE model was validated based on experimental data of sled test and chest-abdomen impact test. High-speed and low-speed sled simulation were conducted to analyze the effect of obesity on impact injury. Compared with normal child model, head and neck injury value of obese child increased. Increased stress and strain of ribcage and internal organs caused the chest and abdomen to be more vulnerable and higher risk of rib fracture. The subsequently comparison of seatbelt force between the normal model and obese model also consisted the formal injury analysis results.