BACKGROUND:Children usually wear school bags when walking, and overweight school bags do harm to the lower extremity and foot, thus affecting the child development. OBJECTIVE:To investigate the effect of obesity on gait characteristics of children wearing school bags during walking. METHODS:Forty pupils were enrolled in accordance with body mass index and China school-age children and adolescents overweight, obesity screening body mass index classification standard, including 20 obese children (body mass index: (28.13±3.4) kg/m2) and 20 non-obese ones (body mass index: (17.44±1.57) kg/m2). The gait parameters of children wearing school bags during walking were measured using a 2-m Footscan Plantar Pressure Plate System from RSscan International. RESULTS AND CONCLUSION: Compared with the non-obese children, the peak pressures under the metatarsal heads II-V, midfoot and heel lateral were significantly higher in obese children wearing school bags during walking (P < 0.05). The time to peak pressures under the toes II-V, the metatarsal heads IV, V and midfoot was also significantly higher (P < 0.05). In addition, the arch index for the foot, and right foot axis angle were significantly larger in the obese children as compared with the non-obese children (P < 0.05). To conclude, obese children wearing school bags during walking have weaker walking stability with flatter foot pattern, the larger foot axis angle and dynamic plantar pressure distribution changes compared with non-obese children, which can result in foot damage.