In the present study, seventy-five healthy children between 1 and 6 years of age were assessed during gait trials at a self-selected speed. Four hundred and sixty-two gait trials constituting five age groups with comparable dimensionless walking speeds were selected. 3D joint moments and the power of the lower limbs were computed and expressed using a dimensionless scaling strategy (according to body weight, leg length and the acceleration of gravity). Statistical analysis was performed to examine inter-group differences. Based on the current results, we concluded the biomechanical maturation of joint dynamics occurred around an age of 4 years for the ankle and between 6 and 7 years for the knee and the hip. Moreover, age group comparisons seemed more appropriate in young children using both the dimensionless strategy and a similar walking speed. Future investigations will be conducted on an older population (i.e., adding children older than 6 years) to clearly define the status of knee and hip biomechanical maturation.