The invention disclose application of a reagent for detecting ENPPI protein in preparation of a high-grad serous ovarian carcinoma diagnosis and prognosis kit, and belongs to the technical field of molecular biology and biomedicine. The ENPPI protein is used as a marker for treatment and prognosis diagnosis, an immunohistochemistry method helps to diagnose high-grade serous ovarian carcinoma, the high-grad serous ovarian carcinoma treatment effect and prognosis is judged, the expression of the ENPPI is negative or weak expression in normal ovarian tissue and ovarian serous cystadenoma while is high expression in high-grade serous ovarian carcinoma, and the expression strength is closely related to a clinical prognosis index. According to the dependency between different expression strength and the high-grade serous ovarian carcinoma prognosis, a patient is processed in a layered way, a judgment basis is provided for development of more effective targeted chemotherapeutics, and the ENPPI has important clinical application and medicinal development value.