Abstract: OBJECTIVE To observe and compare the clinical effect of tigecycline and carbapenems on treatment of severe intraabdominal infection（sIAI） caused by multidrug-resistant organisms（MDROs）. METHODS A total of 68 patients with MDROs sIAI who were treated in intensive care unit（ICU） of the Affiliated Hospital of Nantong University from Jan 2016 to Dec 2020 were enrolled in the study and randomly divided into the tigecycline group with 34 cases（combined drug therapy based on tigecycline） and the carbapenem group with 34 cases（ combined drug therapy based on carbapenems）, both groups were treated for no less than 3 consecutive days. The levels of serum immunoglobulin（Ig） G, IgA, IgM, tumor necrosis factor-α（TNF-α）,interleukin-6（IL-6）, C-reactive protein（CRP） and procalcitonin（PCT） were detected before and after the treatment. After the treatment, the curative effects of the two groups were evaluated, and the incidence rate of adverse reactions and 30-day survival status were recorded. RESULTS The total effective rate and eradication rate of pathogens of the tigecycline group were respectively 76.47% and 73.53%, the total effective rate and eradication rate of pathogens of the carbapenem group were respectively 64.71% and 61.76%, and there were no significant differences between the two groups. The levels of serum IgG and IgM of the tigecycline group were significantly higher than those of the carbapenem group after the treatment（P＜0.05）; the levels of serum IgA, TNF-α, IL-6, CRP and PCT of the tigecycline group were significantly lower than those of the carbapenem group（P＜0.05）. The 30-day survival rate was 73.53% in the tigecycline group, 61.76% in the carbapenem group, and there was no significant difference. The incidence of adverse reaction ns was 17.65% in the tigecycline group, 14.71% in the carbapenem group, and there was no significant difference. CONCLUSION Tigecycline can remarkably boost the immune function of the patients with MDROs sIAI and reduce the levels of inflammatory factors, and there are no significant differences in the effective rate of treatment and eradication rate of bacteria between the tigecycline therapy and the carbapenem therapy.