Objective To study the application value of multi-slice spiral CT (MSCT) image postprocessing techniques in the diagnosis of pulmonary embolism (PE). Methods A total of 38 patients with PE diagnosed by CT pulmonary angiography (CTPA) in our hospital during January 2015 - January 2016 were enrolled in the study. All patients received conventional arterial enhancement scanning with MSCT, the display of pulmonary arteries and emboli was observed. The images obtained through MSCT image postprocessing techniques were treated with multiplanar reconstruction (MPR), maximum intensity projection (MIP) and volume rendering (VR), and the display of pulmonary arteries and emboli was observed again. The results were compared with those of pure MSCT scan. Results All subjects successfully completed the examination. Routine MSCT showed a total of 362 branches of pulmonary artery involvement, and image postprocessing showed a total of 385 branches of the pulmonary artery involvement, including 8 main pulmonary arteries, 35 left and right pulmonary arteries, 78 lobar arteries, 218 segmental arteries and 46 sub segmental arteries. After MPR, MIP and VR image processing, the branch filling defects and other signs of pulmonary artery can be observed clearly. Among 385 branches of pulmonary artery involvement, there were 97.14% (374/385) displayed by MPR, more than (362/385) by MIP and 92.73% (357/385) by VR (P<0.05). Conclusion After routine MSCT scanning, image postprocessing techniques can accurately display emboli and pulmonary artery involvement, and the signs play an important role in clinical diagnosis. The display of sub segmental and lower pulmonary artery emboli by MPR is better than MIP and VR.