Objective To explore the effect of nutrition education based on self-efficacy theory in patients with rectal cancer undergoing prophylactic ileostomy. Methods A total of 66 rectal cancer patients undergoing prophylactic ileostomy were divided into a control group and an intervention group chronologically, with 33 cases in each group. The control group was given routine health education，while the intervention group received nutrition education based on self-efficacy theory. The BMI, laboratory indicators of nutritional status, scores of Patient-generated Subjective Global Assessment（PG-SGA） and stoma self-efficacy between the two groups before the intervention and 1,3 months after the intervention were compared. Results At 1 and 3 months after the intervention, the BMI and laboratory indicators of nutritional status of the intervention group were significantly higher than those of the control group，and the scores of PG-SGA and stoma self-efficacy were significantly better than those of the control group (P<0.05,P<0.01). Conclusion The nutrition education based on self-efficacy theory is conducive to improving the nutrition status of rectal cancer patients undergoing prophylactic ileostomy, and enhancing their stoma self-efficacy level.