Abstract: Objectives　To explore the difference of heart rate deceleration capacity (DC), heart rate acceleration capacity (AC), and heart rate variability (HRV) among overweight children, obesity children, and metabolic syndrome (MS) children. The correlation between body mass index (BMI) and the indexes of DC, AC, and HRV was analyzed. Methods　One hundred three overweight and obesity children over 10 years old were selected. The levels of DC, AC, and HRV were detected in these children. Results　The level of DC (5.97±1.77 ms) in MS group was lower than that in non-MS group (7.93±1.56 ms); the level of AC (?6.78±1.56 ms) in MS group was higher than that in non-MS group (?8.17±1.61 ms²); the level of HF [335.2(157.03~659.33) ms²] in MS group was lower than that in non-MS group [497.5(345.6~767.1) ms²]; BMI (29.64±2.83 kg/m²) was higher than that in non-MS group (26.79±1.83 kg/m²) and the differences were statistically significant (P all < 0.05). The BMI in overweight and obesity children was negatively correlated with DC (r= ?0.241, P=0.014), and was positively correlated with AC (r=0.199, P=0.044). Conclusions　The autonomic nervous function of MS patients is impaired, and the vagus nerve tension is decreased. The protective force on the heart was weaker in the higher degree of overweight, obesity and lower vagus nerve tension, and thus it was the more likely to cause cardiovascular disease.