Abstract: Objective To explore the factors related to platinum resistance in chemotherapy to high-grade serous ovarian cancer. Methods Clinical data about 110 patients with high-grade serous ovarian cancer who underwent primary surgery in our department from January 1,2011 to January 31,2018 were collected.The patients were divided into sensitive (non-recurrent and platinum-sensitive) group and drug-resistant (refractory and platinum-resistant) group according to the NCCN guidelines.The related factors of primary platinum resistance were analyzed. Results Of the 110 patients with high-grade serous ovarian cancer,30 cases (average age of 53.6 years) were in the drug-resistant group and 80 cases (average age of 54.54 years) in the sensitive group.There was no significant difference in age,menopause,parity,sterilization and family history of cancer between the two groups (P>0.05).However,significant differences were found in presentation of gastrointestinal symptom,pathological stage,residual lesion size,ascites,preoperative CA125 level and the positive expression of HER-2 protein between the two groups (all P<0.05).Logistic regression analysis showed that the independent risk factors for primary platinum resistance were presentation of gastrointestinal symptoms (OR,5.909;95% CI,1.636-21.352),residual lesion>1 cm (OR,9.543;95% CI,1.076 to 84.649),advanced clinical stage (OR,10.102;95% CI,1.507-96.548),preoperative CA125>300 U/ml (OR,6.081;95% CI,1.513 to 24.450),and positive expression of HER-2 protein (OR,6.820;95% CI,1.419 to 32.783). Conclusion The risk factors for platinum resistance in high-grade serous ovarian cancer are gastrointestinal symptoms,residual lesion>1 cm,advanced clinical stage,preoperative CA125>300 U/ml,and positive expression of HER-2 protein.