ObjectiveTo summarize the blood routine indexes and predictive systems that can predict the severity of acute pancreatitis (AP). MethodThe recent domestic and foreign literatures on the predictive value of blood routine indexes for the severity of AP were reviewed.ResultsFrom the current research results at domestic and foreign, independent blood routine indexes such as red blood cell distribution width, average platelet volume, hematocrit (TCT), platelet (PLT) count, platelet distribution width, percentage of immature granulocytes (IG%), and some blood routine calculation indexes such as neutrophil to lymphocyte ratio (NLR), PLT to lymphocyte ratio (PLR), red blood cell distribution width to PLT ratio (RPR), neutrophil-monocyte product, and so on, all had different predictive value for the severity of AP. In addition, multiple prediction modes such as blood routine indexes combined with some serological indexes or other scoring systems could also be used to predict the severity of AP. In general, the predictive value of the NLR, IG%, and HCT on the severity of AP had been unanimously recognized by researchers. However, the conclusions of related studies on the predictive values of PLT, PLR, and RPR on the severity of AP were still controversial. ConclusionsAt present, there are a variety of blood routine indexes can be used to predict severity of AP, but their predictive values are different. Further researches are still needed.