Happy Gymnastics is an emerging Sport proposed by the General Administration of Sport of China, which has developed rapidly in recent years. Happy Gymnastics improves children's interest in participating through different teaching methods, cultivates lifelong sports awareness, and enhances children's physical and mental development. This research uses happy gymnastics training as the main method, and by analyzing the influence of happy gymnastics training on the development of children's physical quality, explores a scientific exercise that conforms to the laws of children's physical and mental development to improve children's physical and mental health, and provides a theoretical basis for enriching children's sports programs. In this study, questionnaire survey, experimental method and mathematical statistics method were used for research, and 60children aged 5to 6i n xx kindergarten In Changshu City were subjected to experimental intervention for 16 weeks, with 30people In the experimental group and 30in the control group. The experimental group was given gymnastics training, while The control group was given regular games. The result after The experiment: The data after The experiment showed that The experimental group was better than The control group in The ten-meter reentry running, standing long jump, tennis long throw, continuous jump with both feet, sitting forward bending and walking on The balance beam, and The difference was statistically significant (p < 0.05) . The physical qualities of The experimental group after The experimental intervention were better than those before The experiment, and there were extremely significant differences in The improvement of performance (p < 0.01) . There was a significant difference in the improvement of balance ability in the control group before and after the experiment (p < 0.05) , and There was no significant difference in other physical qualities (p > 0.05). The study came to The following conclusions: Through 16-week experimental research, Happy Gymnastics training can effectively promote the development of children's agility, explosiveness, muscle strength, coordination, flexibility and balance, especially the improvement of lower extremity explosiveness and flexibility.