Abstract: Objective: To summarize X-ray and CT imaging characteristic for pelvic fracture and analyze the missed diagnosis reason. Methods: Retrospectively analyzed 620 cases of pelvic fracture with X-ray and spiral CT image data,to compare detection rate and analyze the missed diagnosis reason. Results: There were 1036 fractures in quantity and 38 dearticulation of 620 cases. 255 iliac fractures,226 acetabular fractures,99 sacral and coccyx fractures,341 pubic upper and lower branches fractures,115 ischia fratures,20 cases of dislocation of hip joint and sacroiliac joint. About 169 micro-fractures,1 post dislocation of hip joint,5 mild dislocations of sacroiliac joint and 3 mild separation of pubic symphysis were mis-diagnosed by X-ray. Fracture detection rates of X-ray plain is 83.7% and dislocation detection rates is 76.3%;Among 226 acetabular fractures,X-ray plain and SSD mis-diagnosed about 61 and 20 fractures separately. The detection rate of X-ray plain and SSD of fracture was 73.0 % and 91.2%. In 99 sacral and coccyx fractures,X-ray plain and SSD mis-diagnosed about 48 and 11 cases,the fracture-dislocation detection rate was 56.0% and 89.9% separately. Through χ² examination,X-ray plain and CT of pelvic fracture had differences in statistically(p<0.05). There's no statistical difference between SCT/MPR and SSD(p>0.05). Conclusion: The performance of spiral CT is better than X-ray examination in the detection of pelvic fracture. Spiral CT with MPR and SSD could clearly reveal the detail of fracture,improved the preoperative diagnosis and facilitated surgical treatment.