Ovarian leiomyoma is a rare type of tumor that only takes about 1% of benign ovarian tumor. It mostly does not induce any symptoms and is often found by chance during a surgical operation in abdominal cavity. It is microscopically observed that smooth muscle cells with an identical shape and a small nucleus grow in a bundle or in a storiform configuration, and they need to be distinguished from other tumors of the smooth-muscle origin that can occur in ovary such as fibroma/thecoma and extragastrointestinal stromal tumor. Using immunohistochemistry staining on desmin, smooth muscle actin (SMA), alpha-inhibin, c-kit, etc can help with distinguishing these tumors. Recently, the authors experienced in this hospital a primary ovarian leiomyoma of a 43-year-old female patient and hereby report the case with a review of literatures.