Objective To investigate the diagnostic value of multi-slice spiral CT plain scan and three phase dynamic enhanced scan in retroperitoneal schwannoma. Methods A total of 48 patients with retroperitoneal schwannoma treated in our hospital from January 2013 to December 2016 were selected. The clinical data and imaging data of 48 patients were collected, analyze the 48 cases of retroperitoneal schwannoma CT scanning images, and the pathological examination results as the standard, compared with unenhanced CT scanning rate detection and diagnosis of retroperitoneal schwannoma and the accuracy rate of CT three enhanced. Results The detection rate and accurate diagnosis rate of CT scan for retroperitoneal schwannoma were 79.16% (38/48) and 72.91% (35/48), the detection rate and accurate diagnosis rate of retroperitoneal schwannoma with three phase CT enhancement were 97.91% (47/48) and 95.83% (46/48), the detection rate and accurate diagnosis of retroperitoneal schwannoma with CT three phase scan were significantly higher than that of CT plain scan, the difference was statistically significant (P<0.05). CT scan showed round or oval shape, part of the nodular lesion with low density, there were cystic low density, 12 cases (28%) patients with visible adjacent intervertebral foramen, compression bone absorption, completely solid tumor density than all;The cystic wall is thin and the internal and external wall are all smooth; the cystic solid image shows that the solid components appear low density. Enhanced CT scanning average tumor entity region venous phase (52.5+8.25) HU value, the average value of CT arterial phase (52.5+8.25) HU, the majority of patients in the visible mass enhancement scanning edge enhancement is uniform, internal enhancement was cloudy, mild enhancement in venous phase, further mild progressive enhancement, sagittal reconstruction of visible lesions on the edge of the low density and mass connected, forming a typical nerve like syndrome. Conclusion The three slice dynamic enhanced CT scan has a high detection rate and high accuracy in the diagnosis of retroperitoneal schwannoma. It can clearly show the size of the lesion, the internal structure and the anatomy of the adjacent organs.