To evaluate the effects of oral nutritional supplement therapy ONS on nutritional status and immune function for patients with ovarian cancer after surgical resection and routine intravenous chemotherapy and put forward a reasonable nutritional supply scheme. Method A total of 102 patients with ovarian cancer who were admitted to Affiliated Hospital of Jiangnan University from January 2018 to December 2021 were prospectively selected by clinical randomization case-control method and all of them were treated with surgical resection and conventional intravenous chemotherapy. Then they were randomly divided into control group and test group with 51 patients in each group. The control group was given routine nutrition guidance and the test group was given ONS Ensure ® 250 ml 1. 06 kcal containing 0. 0356 g protein per mL produced by Abbott Laboratories in the United States 3 times/ d for 15 weeks. The body mass body mass index BMI serum lymphocyte count erythrocyte count hemoglobin albumin and total protein levels before discharge 3 weeks 9 weeks and 15 weeks after discharge as well as the Patient generated subjective overall assessment PG-SGA score were compared between the two groups. Result 48 patients in the control group and 49 patients in the test group finally completed the clinical follow-up. The general clinical datas of the two groups were comparable P > 0. 05 . The body mass and BMI of the test group were significantly higher than those of the control group after 9 and 15 weeks follow-up the levels of serum lymphocyte count erythrocyte count hemoglobin albumin and total protein were significantly higher than the control group and the PG-SGA score was significantly lower than the control group too P < 0. 05 . Conclusion Patients with ovarian cancer have a higher risk of malnutrition after surgical resection and routine intravenous chemotherapy. Routine ONS is of positive significance to improve the nutritional and immune status of the body which is worthy of clinical application.