Ewing's sarcoma of the spine is an uncommon but highly lethal rumor. The time from the onset of symptoms to definitive diagnosis is long, and the presentation often is more dramatic because of the rare incidence of neurologic problems associated with spinal location. We present a case of Ewing's sarcoma is sacrum and presacral area with the clinical symptoms of low back pain and cauda equina syndrome. The literatures are reviewed, and the diagnosisi, management and prognosis are disussed.