Objective To evaluate the changes of left ventricular myocardial work in overweight and obese patients by using non-invasive left ventricular pressure strain loops (PSL) technology, and to explore the clinical value of myocardial work in the assessment of left ventricular myocardial function impariment in obese patients. Methods A total of 64 obese patients were collected from the outpatients and inpatients of Bariatric Metabolic Surgery in our hospital as the observation group. According to BMI, the obese patients were divided into overweight group (24kg/m2≤BMI <28kg/m2) and obese group (BMI ≥ 28kg/m2), with 32 cases in each group and 46 healthy volunteers were collected as the control group. Echocardiography was performed in all groups. the Global longitudinal strain (GLS) were obtained by speckle tracking technique, and the myocardial work parameters were obtained by PSL technique, including the global work index(GWI), global constructive work (GCW), global waste work(GWW) and global work efficiency(GWE). Left ventricular routine echocardiography and myocardial work parameters among the three groups were compared, and the correlation between myocardial work parameters with GLS and BMI was analyzed. Result ① Routine echocardiographic parameters: There were no significant differences in routine echocardiographic parameters among the three groups (all P>0.05). ②Strain parameters and myocardial work parameters: compared with the control group, GLS, GWI and GCW were decreased in overweight groups and obese groups (P<0.05), while GWW was increased (P<0.05). GLS, GWI and GCW decreased and GWW increased significantly in obese groups compared with overweight groups(P<0.05). ③ Correlation analysis: GLS was positively correlated with GWI and GCW (r=0.875, 0.833, P<0.001), but negatively correlated with GWW (r = -0.879, P<0.001), and had no correlated with GWE (P>0.05). GLS, GWI and GCW were negatively correlated with BMI (r = -0.861, -0.744, -0.763, all P<0.05), GWW was positively correlated with BMI (r = 0.897, P<0.05), and GLS had the highest correlation with BMI. Conclusion The myocardial function of overweight and obese patients was significantly reduced . PSL technology can early reflect the damage of left ventricular systolic function in obese patients, and the higher the BMI, the more serious the damage of left ventricular systolic function.