Low-grade endometrial stromal sarcoma (LGESS) with intravascular extension is very rare, with only 26 cases having been reported. We experienced a case of LGESS with inferior vena cava (IVC) extension. A 60-year-old female presented with left leg edema. She had a history of total hysterectomy, and was diagnosed of leiomyoma at that time. On imaging study, tumor masses were located around both common iliac veins (CIV), and within the CIV and IVC. The pelvic masses on both side and IVC mass were resected, and then the patient received adjuvant hormonal therapy and radiotherapy over the remnant pelvic masses. LGESS with IVC extension is difficult to distinguish from intravascular leiomyomatosis. LGESS is a malignant disease and commonly recurs, even in early stages. Accurate diagnosis, complete resection, proper adjuvant therapy and close follow-up are very important.