Objective To evaluate the effect of exercise-diet behavior intervention based on the transtheoretical model in patients undergoing weight loss surgery.Methods By convenience sampling,72 patients undergoing weight loss surgery in a tertiary general hospital in Xinxiang City,Henan Province from February 2021 to October 2022 were selected as the research subjects.By a random number table method,they were divided into a test group and a control group,with 36 cases in each group.The test group received exercise-diet behavior intervention based on the trans-theoretical model,while the control group received conventional intervention.The intervention began on the first day after admission and ended 6 months after surgery.The body mass index,body fat,lean body mass,diastolic blood pressure,systolic blood pressure,fasting blood glucose,insulin resistance index(HOMA-IR),Health Promoting Lifestyle Profile-Ⅱ(HPLP-Ⅱ)score,and Short-Form-36 Health Survey(SF-36)score were compared between the 2 groups before and after surgery for 3 and 6 months,as well as the complications within 6 weeks after surgery.Results The results of repeated measures analysis of variance showed that there was an interaction between the 2 groups in terms of anthropometric measurements,blood pressure and blood glucose,HPLP-Ⅱ scores,and SF-36 scores,with statistically significant differences(P＜0.001).After 6 months of surgery,the body mass index(23.32±2.32),body fat(24.10±3.46)kg,and lean body mass(41.64±3.24)kg in the test group were lower than(27.32±3.64),(28.46±4.18)kg,and(46.68±4.65)kg in the control group,and the differences were statistically significant(P＜0.001).At 3 and 6 months after operation,the diastolic blood pressure,systolic blood pressure,fasting blood glucose and HOMA-IR of the test group were lower than those of the control group,and the differences were statistically significant(P＜0.05).The HPLP-Ⅱ score of the test group was higher than that of the control group at 3 and 6 months after operation(P＜0.001).The SF-36 score of the test group was significantly higher than that of the control group at 6 months after operation(P＜0.05).The incidence of complications in the test group was 2.56％,which was not significantly different from 19.44％in the control group(P＞0.05).Conclusion The exercise-dietary behavior intervention based on the transtheoretical model can promote the formation of healthy behaviors in patients undergoing weight loss surgery,maintain weight loss effects,improve blood pressure and blood glucose levels,and enhance the quality of life of patients.