Objective To investigate the effects of gender and body mass index(BMI) on dynamic plantar pressure among children by comparing the plantar pressure parameters of obese boys and girls, as well as normal boys and girls when walking at preferred speed on flat ground and reviewing the relativity of children’s BMI and these parameters. Method 79 children were enrolled in this research to make gait test when walking naturally, using a 0.5m footscan plate system (RSscan International, Belgium). The results were statistically processed and analyzed by SPSS16.0. Results(1) There is no significant difference in mostly dynamic plantar pressure parameters between genders for both obese and normal children; (2) There is significant difference in the impulse percentage in mid foot and ground, and appearing time of pressure peak values of several areas including M5, MF and HL for normal children; (3) There is no significant correlation between BMI and foot support duration, impulse percentage between mid foot and ground, pressure peak value of T25, appearing time of pressure peak value of HM and HL; (4) BMI and the other plantar pressure distribution indicators are well correlated. Conclusions(1) There is no significant difference on dynamic plantar pressure distribution between genders for obese children, but there are effects of genders on partial dynamic plantar pressure distribution parameters for normal children; (2) Children with larger BMI are of worse walking stability and lower efficiency; (3) Children with larger BMI tend to feel fatigue in walking and get injured in ankle joints and other parts of the body more easily.