Objective To explore imaging features of pure ovarian dysgerminoma. Methods The clinical, CT and MRI findings in 15 pure ovarian dysgerminoma patients, confirmed by operation and pathology, were retrospectively analyzed. The imaging features and diagnosis were also discussed. Results The age range from 6 to 23 years(median age,16 years). 15 patients underwent CT plain scan and three-phase dynamic enhanced scan. In CT plain scans, 5 cases were in homogeneous density, 8 cases and 2 cases were small or large patchy necrosis of center. 6 cases had spot or strips calcification within the tumor. After contrast administration, solid part of tumors showed slight enhancement in arterial phase and mild degrees of delayed enhancement in venous phase and delayed phase in 14 cases. Among those, 9 cases demonstrated the vascular septa, arising from the ovarian arteries. In another case, the tumor was significantly enhanced at arterial phase, and was continuous enhanced in venous phase and delayed phase. The plain and enhanced MRI were performed in 4 cases. The main MRI features of the fibrous septa showed low signal in both T1WI and T2WI. After contrast administration, the capsule of tumors and fibrovascular septa was significantly enhanced. Pelvic lymph node metastasis was found in 1case, and retroperitoneal lymph nodes and rectovaginal pouch metastasis in 1 case, respectively. The serum HCG and LDH levels were significantly increased in 6 cases and 2cases, respectively. Conclusion The disease should be considered for pure ovarian dysgerminoma combined with the significantly increasing of the serum β-HCG or LDH levels, homogeneous density tumor of ovarian in a young adult women, hypervascular with mild enhancement, especially, the fibrovascular septa and capsule were showed on MRI examination. Enhanced CT scan manifested vascular septa within tumor has some value for diagnosis of pure ovarian dysgerminoma.