Ovarian cancer (OC) is the most lethal gynecologic malignancy, attributed by late diagnosis. Genetic alteration of BRCA1/2 was well known risk factors in people who does not occur ovarian cancer. There is a need for convenient and continuous diagnosis of ovarian cancer after genetic testing, and we intend to apply a blood biomarker-based liquid biopsy. In a retrospective study, 20 OC patients and 20 normal controls were used for plasma samples, and BRCA1/2 carriers accounted for half in each group. We applied the bottom-up proteomics approach to depleted plasma samples with a nano-flow LC-MS and analyzed protein data quantitatively.