Objective: To investigate the effect of gross motor skills on physical activity of children aged 3-6 years, and to provide basis for children’s health behavior intervention. Methods: A total of 332 young children in Shanghai Xiangyin kindergarten were selected as survey objects. The development of gross movements of young children was measured by TGMD-2. Caregivers reported children’s physical activity using the International Physical Activity Questionnaire (IPAQ-SF). Results: The development level of gross movements of children aged 3-6 in Shanghai was relatively low(54.76±13.86). The physical activity of children was mainly light-intensity physical activity, and the daily moderate-to-vigorous intensity physical activity time was (58.62±52.73) minutes every day. Locomotor skills had the greatest effect on children’s VPA (β=0.19) and TPA(β=0.12), with a contribution rate of 3.3% and 1.1%, respectively; Object control skills has the greatest effect on children’s MVPA (β=0.17) and MPA (β=0.12) had the largest effect(P<0.05), with contribution rates of 2.5% and 1.2%, respectively. The relationship between gross motor skills and physical activity had nothing to do with gender and age. Conclusion Children’s gross motor skills in the 3-6 year-old population should be improved and may be an effective way to promote physical activity.