Abstract: OBJECTIVE To explore the risk factors for concurrent spontaneous bacterial peritonitis (SBP) in the patients with decompensated cirrhosis (DCC) and observe the expression levels of peripheral blood neutrophil-lymphocyte ratio (NLR) and monocyte/lymphocyte ratio (MLR). METHODS A total of 246 DCC patients who were complicated with SBP and treated in Infectious Disease Department， General Hospital of Ningxia Medical University from Feb. 2020 to Feb. 2025 were recruited as the research subjects and were divided into the survival group with 174 cases and the death group with 72 cases according to the treatment outcomes between the admission to the hospitals and the 90-day follow-up. The distribution of pathogens isolated from ascites of the patients was retrospectively analyzed. Multivariate logistic regression analysis was performed for the risk factors for the short-term prognosis of the patients. Receiver operating characteristic (ROC) curves were drawn to analyze the efficacies of NLR and MLR in prediction of the short-term prognosis， and the relationship between NLR， MLR and the short-term prognosis was analyzed by Kaplan-Meier. RESULTS Among the 246 patients， 42 (17.07%) were positive for culture of ascites. Totally 66 strains of pathogens were isolated， of which 41 (62.12%) were gram-negative bacteria， predominated by Escherichia coli. The result of multivariate logistic regression analysis indicated that complication with gastrointestinal hemorrhage (OR=2.138) and Child-Pugh score(OR=1.782) were the risk factors for the poor short-term prognosis(P＜0.05). The ROC curve analysis indicated that NLR and MLR had certain values in prediction of short-term prognosis of the DCC patients complicated with SBP， and the predictive value of the combination of the two indicators was highest(P＜0.05). Kaplan-Meier survival analysis showed that the survival rate was low in the high NLR group and the high MLR group (P＜0.05). CONCLUSION NLR and MLR are effective for diagnosis of SBP in the DCC patients and prediction of prognosis， they can independently predict the risk of short-term death， and the combination of the two indicators can remarkably raise the accuracy of prognosis assessment.