Objective To study the safety and short-term clinical outcome of different body mass index (BMI) patients with rectal cancer undergoing laparoscopic total mesorectal excision (TME). Methods The clinical data of 179 rectal cancer patients who had underwent laparoscopic TME from November 2016 to November 2017 were retrospectively analyzed. The patients were divided into 3 groups according to the BMI:leanness group (BMI<18.5 kg/m2, 15 cases), normal group (BMI 18.5 to 22.9 kg/m2, 89 cases) and overweight/obesity group (BMI ≥23.0 kg/m2, 75 cases). The general clinical data and the operation-related situation were compared. Results The rate of preoperative complications in overweight/obesity group was significantly higher than that in leanness group and normal group: 45.33％(34/75) vs. 4/15 and 28.09％(25/89), the preoperative albumin level in leanness group was significantly lower than that in normal group and overweight/obesity group:(36.3 ± 2.8) g/L vs. (38.6 ± 3.2) and (39.1 ± 3.7) g/L, and there were statistical differences (P<0.05). The operation time and blood loss in overweight/obesity group were significantly higher than those in leanness group and normal group: (149.2 ± 32.9) min vs. (129.3 ± 28.7) and (133.5 ± 23.6) min, (135.5 ± 29.0) ml vs. (117.5 ± 22.6) and (122.5 ± 25.9) ml, and there were statistical differences (P<0.05). There were no statistical differences in sex, age, tumor location, tumor maximum diameter, depth of tumor invasion, lymph node metastases, surgical approach, circumferential margin, number of lymph node dissections, length of resected specimens, incidence of postoperative complications, surgical site infection, postoperative urinary retention, postoperative exhaust time and postoperative hospitalization among 3 groups (P>0.05). Conclusions The differences of BMI mean different complications and nutritional status of patients. Overweight and obesity can lead to difficult operation of laparoscopic TME, but do not affect the radical cure of operations and the safety of clinical outcomes.