Objective: To evaluate the prevalence and prognostic value of platelets and fibrinogen in preoperative patients with epithelial ovarian cancer (EOC). Methods: This study enrolled 297 patients with epithelial ovarian tumor admitted to our hospital from June 2012 to June 2016 who underwent operative therapy, among which 137 patients were malignance as the experimental group and 160 were benign as the control group. We retrospectively collected the basic information of EOC, including age, preoperative laboratory tests (blood routine, coagulation function and CA-125), the volume of ascites and tumor size measured during the surgery, postoperative pathologic records, and analyzed the correlation between thrombocytosis and high fibrinogen with clinical pathologic factors by evaluating the incidence of thrombocytosis and high fibrinogen. All patients diagnosed with EOC were followed to June 2017, the overall survival (OS) and progression free survival (PFS) were calculated, and the relationship between thrombocytosis and high fibrinogen and prognosis was analyzed. Results: The content of platelets and fibrinogen in patients with EOC was significantly higher than that in patients with benign ovarian tumors (P<0.05). International Federation of Gynecology and Obstetrics (FIGO) pathological stage is later, the lower the degree of differentiation, the amount of ascites, more postoperative residual tumor size, preoperative CA125 level, preoperative tumor volume smaller in patients with thrombocytosis rate was higher (P<0.05); fibrinogen increased with FIGO pathological stage, ascites the amount of postoperative residual correlated with tumor size and preoperative CA125 level (P<0.05). Thrombocytosis is an independent prognostic factor for progression free survival in patients with epithelial ovarian cancer (P<0.05). There is no correlation between fibrinogen and prognosis in patients with epithelial ovarian cancer. Conclusion: Thrombocytosis and high fibrinogen are prevalent in patients with EOC, which may owe to the invasion and metastasis of cancer. Thrombocytosis is an unfavorable prognostic factor of survival in patients with EOC.