Objective To compare the parameters of plantar pressures between the obese children and normal children during walking on the flat ground at normal speed, and to discuss the effect of obesity on dynamic plantar pressures for 7-11 years obese children. MethodThere were 40 volunteer subjects, twenty obese children and twenty normal children between 7 and 11 years of age in this study. Subjects were asked to walk at their own paces on a 10 m walkway with a 0.5 m footscan plate (footscan from RSscan International, Olen, Belgium) Sampling at 300 Hz. Data were processed statistically by SPSS11.5 and EXCEL. ResultsCompared to the normal children: 1.the obese children have the longer foot support duration and shorter pushoff duration; 2.the peak plantar pressures are larger and appearing time is longer of Metatarsal 4 (M4) and Metatarsal 5 (M5), the peak plantar pressures of Toe 2 (T2) to Toe 5 (T5) on obese children group are higher. 3. AI (arch index) and impulse percentage of midfoot and heel of obese children group are much larger. 4. Supination extent of the left foot in heel strike phase, supination extent of the right foot in footsupport phase and in pushoff phase on obese children group are also larger. In addition, significant difference in pronation extent appeared between left and right foot in obese children group. 5. The footaxis angle of obese children group is obviously larger. ConclusionsCompared to the normal children: 1. the walking stability of obese children group in this study is weaker. 2. Obese children are vulnerable to injure their foot foresole, ankle joint and knee joint. 3. Obese children endure flat foot more easily. 4. Obese children walk more frequently with outward splayfoot.