Abstract: Primary retroperitoneal yolk sac tumor is a rare disease in clinical setting, which is likely to be misdiagnosed or miss the diagnosis. In this article, a 25-year-old woman who was pathologically diagnosed with primary retroperitoneal yolk sac tumor was reported. She was admitted to our hospital due to abdominal distention for one week. Preoperative imaging examination suggested the possibility of malignant ovarian tumor. During the exploratory open surgery, it was found that the tumor was derived from the retroperitoneum, and no tumor was found in both ovaries. The tumor was surgically removed. According to the treatment of yolk sac tumor, chemotherapy consisting of etoposide 150 mg + carboplatin 900 mg + bleomycin 15 mg （BEP） was delivered for 6 cycles. After the third cycle of chemotherapy, the alpha-fetoprotein （AFP） level was decreased to normal range. No abnormal tumor was found by color Doppler ultrasound. No tumor recurrence was observed during 1-year follow-up. This case prompts that imaging examination combined with AFP detection contribute to clinical diagnosis and prognosis evaluation of primary retroperitoneal yolk sac tumor. Surgery in combination with chemotherapy yields high clinical efficacy.