Objective To analyze the differences in clinical signs and multi-slice spiral CT (MSCT) findings of patients with gangrenous appendicitis, suppurative appendicitis and simple appendicitis. Methods The clinical data of 90 patients with acute appendicitis admitted in our hospital during September 2013 to September 2015 were analyzed retrospectively. Among them, there were 41 cases with acute simple appendicitis, 37 cases with acute suppurative appendicitis and 12 cases with acute gangrenous appendicitis. All patients underwent MSCT scan before operation. The MSCT findings of all patients were analyzed and compared with the final pathological findings. The MSCT findings were compared between patients with different pathological types of acute appendicitis. Results CRP, white blood cell count and percentage of neutrophilsin simple appendicitis group were significantly lower than those in suppurative appendicitis group and gangrenous appendicitis group (P<0.05). CRP, white blood cell count and percentage of neutrophilsin suppurative appendicitis group were significantly lower than those in gangrenous appendicitis (P<0.05). MSCT of simple appendicitis showed slight swelling of appendix, unclear edges of appendix and liquid-like shadow in the lumen; Suppurative appendicitis showed obvious swelling, fuzzy boundaries, visible flocculent and strip like shadows, cecal wall thickening; Gangrenous appendicitis showed obvious thickening, obvious periappendiceal pneumatosis, appendix and cecum wall thickening and blurred boundaries. Conclusion The clinical manifestations of different pathological types of acute appendicitis were atypical while MSCT findings are typical differences. MSCT is of high guidance value in the diagnosis of different pathological types of acute appendicitis and is worthy of clinical application.