Borderline ovarian tumor with the initial presentation of pseudo-Meigs' syndrome is rare. A 52-year-old postmenopausal woman presented with a large ovarian tumor, ascites, and right hydrothorax. We found elevated serum carcinoembryonic antigens (44.4 ng/mL), carbohydrate antigen (CA)-125 (269.8 U/mL), and CA-199 (7942 U/mL). The frozen section pathology revealed a mucinous borderline ovarian tumor, and a staging operation was performed. Final pathologic examination confirmed the diagnosis of intestinal type ovarian mucinous borderline tumor with non-invasive cul-de-sac implants. Her pleural effusion and ascites resolved after surgery, and she remained tumor-free after 3 years' follow up. Physicians should be cautious for the rare possibility of pseudo-Meigs' syndrome in patients with pelvic tumors having the features of advanced ovarian cancer.