Background: Microcystic stromal tumor is a recently described subtype of ovarian tumor characterized by microcystic pattern and diffuse immunoreactivity for CD10, vimentin, and beta-catenin and negative for EMA. However, its diagnostic criterion and standard treatment remain unclear. Case presentation: We report a rare case of a left side microcystic stromal tumor with diameter about 7 cm in a 25-year-old female and summarize all cases of MCST reported in this study. The present patient underwent left ovarian tumor resection. Generally, the tumor was solid and cystic mixed. Immunohistochemically, the tumor was expressed CD10, WT1, cyclin D1 and vimentin, and nuclear immunoreactivity for beta-catenin but negative for alpha-inhibin, calretinin, CK AE1/AE3, PLAP, SALL-4, CK7, P53, EMA, CD99, AFP, desmin, CgA, E-cadherin, and melanA. Conclusion: Unilateral ovary, solid-cystic, and a larger than 4-8 cm pelvic mass without serious abdominal pain are its clinical features. The immunophenotype of vimentin+/CD10+/WT-1+/beta-catenin+(nuclei)/cyclin D1+ is supportive of diagnosis. For these patients, unilateral oophorectomy dissection could be selected.