Objective To investigate the physical fitness status and associated factors among preschool children aged 3 to 6 years in Tongzhou District of Beijing, and to provide evidence for promoting physical development in this population.

Methods Based on the 2020 National Physical Fitness Surveillance data for Tongzhou District of Beijing, a total of 416 children were included for standardized physical tests, including morphological, physiological, and fitness indicators, and questionnaire surveys. Independent sample t-tests and ANOVA were used to compare differences in physical indicators across groups, while multivariate linear regression models were applied to analyze influencing factors.

Results The comprehensive fitness score of children aged 3 to 6 years old in Tongzhou District of Beijing was (79.98±6.97) points, with an overall physical fitness pass rate of 99.52%. The proportions of excellent, good, and pass grades were 37.50%, 39.90%, and 22.12%, respectively. The average heights for the 3-years-old, 4-years-old, 5-years-old, and 6-years-old groups in Tongzhou District were (102.13±4.24) cm, (107.92±4.66) cm, (115.43±4.70) cm, and (119.16±4.33) cm, respectively. The corresponding average body weights were (16.63±2.46) kg, (18.66±2.54) kg, (21.60±4.02) kg, and (23.46±4.64) kg, respectively. Among children aged 3 to 6 years, the average BMI was (15.95±1.79) kg‧m^-2, body fat percentage was (21.92±4.77)%, resting pulse rate was (95.24±9.70) beats per minute, grip strength was (5.74±2.07) kg, standing long jump distance was (78.12±19.95) cm, sit-and-reach flexibility was (12.25±4.65) cm, continuous two-foot jump time was (6.29±2.55) seconds, 15-meter obstacle shuttle run time was (7.94±1.30) seconds, and balance beam walking time was (5.11±2.25) seconds. Multiple linear regression analyses showed that higher composite fitness scores were significantly positively associated with female gender (b=1.72, 95%CI: 0.42-3.01), aged 4 years old and above (b=2.97, 95%CI: 1.35-4.59), mixed feeding (b=4.16, 95%CI: 1.60-6.72) or breastfeeding (b=3.23, 95%CI: 0.36-6.10) during infancy, taller paternal (b=0.16, 95%CI: 0.02-0.30) and maternal (b=0.25, 95%CI: 0.11-0.39) height (all P<0.05).

Conclusion The physical fitness of children aged 3 to 6 years in Tongzhou District of Beijing is generally favorable, with gender, age, feeding patterns, and genetic factors identified as key correlating factors. Comprehensive strategies are recommended to improve early childhood physical health.