Objective To investigate the effects of enteral nutrition on cancer cell shedding intestinal flora and immune function in patients with colorectal cancer. Method A total of 300 patients with colorectal cancer who underwent radical surgery in Xinhua Hospital Affiliated to Dalian University from March 2022 to March 2023 were selected as the study objects and were divided into experimental group given enteral nutrition and control group given traditional intestinal preparation according to random number table method with 150 cases each. The positive rate of exfoliated cells in abdominal cavity and intestinal cavity intestinal tolerance and intestinal cleanliness were compared. The intestinal flora bifidobacterium lactobacillus Escherichia coli enterococcus total protein TP prealbumin PA albumin ALB CD4 + CD8 + were observed before and 7 days after surgery and the CD4 + / CD8 + ratio was calculated. Result The positive rates of exfoliated cells in abdominal cavity and intestinal cavity of experimental group were 4. 67% and 10. 67% respectively which were significantly lower than those in control group P<0. 05 . The overall intestinal tolerance Grade Ⅰ/ Ⅱ/ Ⅲ and intestinal cleanliness GradeⅠ/ Ⅱ/ Ⅲ/ Ⅳ between the two groups were statistically significant P < 0. 05 . The quantity of bifidobacterium and lactobacillus was higher than that before operation but the quantity of Escherichia coli and enterococcus was lower than that before operation P<0. 05 . The levels of CD4 + CD8 + CD4 + / CD8 + TP PA and ALB in experimental group were higher than those before surgery P< 0. 05 . The levels of bifidobacterium lactobacillus Escherichia coli Enterococcus CD4+,CD8 + CD4 + / CD8 + TP PA and ALB were 7. 65±0. 68 log GFU/ g 8. 56±1. 45 log GFU/ g and 8. 28±0. 97 log GFU/ g 41. 03±2. 21 % 26. 25±2. 07 % 1. 92±0. 28 69. 52±6. 82 g / L 266. 36±9. 58 mg / L 40. 01±3. 69 g / L The control group was 6. 19±0. 42 log GFU/ g 6. 08±0. 43 log GFU/ g 9. 31±1. 72 log GFU/ g 9. 01±1. 21 log GFU/ g 30. 14±1. 48 % 18. 01±1. 51 % 1. 50±0. 19 62. 01±4. 05 g / L 217. 08±8. 41 mg / L 31. 82±3. 12 g / L compared between the two groups Bifidobacterium lactobacillus CD4 + CD8 + CD4 + / CD8 + TP PA ALB were higher in experimental groups and Escherichia coli and Enterococcus were lower the difference was statistically significant P<0. 05 . Conclusion Preoperative enteral nutrition in patients with colorectal cancer is beneficial to reduce the positive rate of cancer cells shed in abdominal cavity and intestinal cavity correct gastrointestinal flora improve nutritional status and immune function and is of great significance for guiding clinical treatment and improving prognosis.