Objective: To investigate the differences in gastric motility function among populations with different body mass index (BMI) levels using gastric filling ultrasound, clarify the independent impact of BMI on gastric motility, and provide a basis for the research on the mechanism of obesity-related gastric motility disorders.Methods: A total of 100 subjects with BMI ≥ 25.0 kg/m2 were enrolled and divided into Group A (overweight group: 25.0 kg/m2 ≤ BMI 0.05). Within 3~5 minutes after drinking contrast agent, compared with the control group, Group A and Group B showed significant decreases in gastric peristaltic wave peak intensity (1.02±0.29 vs. 0.71±0.30 vs. 1.34±0.38) cm, gastric peristaltic velocity (0.28±0.08 vs. 0.24±0.07 vs. 0.31±0.07) cm/s, MI (0.35±0.11 vs. 0.28±0.10 vs. 0.45±0.23) cm2/s, and number of gastric peristalsis (6.15±1.28 vs. 5.61±1.32 vs. 6.72±1.29) times/2 minutes. Moreover, these indicators in Group B were lower than those in Group A, with statistically significant differences (P Group A > Group B”, with statistically significant differences (P0.05).Conclusion: After excluding confounding factors, BMI is negatively correlated with gastric motility function. The higher the BMI, the weaker the gastric peristaltic capacity and gastric emptying efficiency. Gastric filling contrast-enhanced ultrasound is a potential preferred examination method for evaluating gastric motility function in populations with different BMI levels due to its real-time, non-invasive, highly operable, and reproducible characteristics.