Objective: To demonstrate the effect of structured and autonomous sports activities on children s basic motor skills in a preset outdoor field for a certain time and frequency, and to provide a reference for improving children s development of basic motor skills. Methods: Selected 141 typical developing children from 4 public kindergartens in Nanning, and randomly divided them into experimental group(71) and control group(70). The experimental group participated in physical activities for 10 weeks (3 times a week, 1 hour each time) in the preset outdoor field (each physical activity was composed of 30 minutes of autonomous physical activity and 30 minutes of structured physical activity), while the control group had no intervention of site preset and specially designed activities. Before and after the experiment, 9 basic motor skills (including 3 fine motor skills and 6 gross motor skills) were tested. Results: There were significant differences in double hand throwing, single leg balance (left), single leg balance (right), swing bridge balance and beam walking before and after intervention in experimental group(t=7.82,4.25,9.69,-10.01,-28.28,P<0.05), but there was no statistical significance in the improvement of heel toe coordinated walking(t=-0.60,P>0.05). There was no significant improvement in coin throwing (right hand), coin throwing (left hand) and square stacking(t=0.91,1.03,0.42,P>0.05), while in the control group, except for the balance of swinging bridge(t=4.27,P<0.05) and heel and toe walking(t=3.96,P<0.05), the improvement of other basic motor skills was not statistically significant(t=1.21, 0.74, 0.31, 0.97,P>0.05). Conclusion The quality of sports environment has a potential impact on the basic motor skills of preschool children. The basic motor skills of the pre-school children can be greatly improved by conducting structural and autonomous physical activities with a certain time and frequency.