Abstract: Objective: To investigate the multi spiral computed tomography(MSCT) features of tuberculosis peritonitis(TBP) and carcinomatous peritonitis(CP) so as to improve the level of their diagnosis and differential diagnosis. Methods: Computed tomography imaging materials of 22 patients with tuberculous peritonitis and 45 patients with carcinomatous peritonitis confirmed by surgery and pathology between September 2010 and September 2011 were analyzed retrospectively. Chi-square test was applied to compare the incidence rates of various MSCT features in TBP and CP patient, and the results were compared again with pathological and clinical results.Results The incidences of large amount of ascites were significantly different between TBP group and CP group of patients(41.7%, 72.3%, χ²= 6.343, P = 0.012). The proportions of thickening parietal peritoneum and mesenterium cases were also statistically different among the two groups(P ＜ 0.01), however, the imaging findings of mesenteric nodes showed no significant difference between TBP group and CP group(P ＞ 0.05). In the TBP patients, the main manifestations were smooth thickening parietal peritoneum, and mottled soft-tissue densities in the mesenterium. In the CP patients, the main manifestations were nodular thickening of the parietal peritoneum. There was a statistical difference in the thickness of the greater momentum between the two groups of patients(P ＜ 0.01).Conclusions Based on the parietal peritoneum changes, comprehensive analysis of the greater momentum, mesenterium and ascites is helpful in and differential diagnosis of two diseases.