Severe acute pancreatitis (SAP) has many challenges in the clinical management of ICU. The severity and prognosis of the disease often depend on the early inflammatory reaction. About 30% of patients die of severe bacterial infection or organ failure. Studies have shown that SAP patients have suffered from systemic immunosuppression and intestinal immune barrier damage in the early course of disease, which may lead to infectious complications such as infectious necrotizing pancreatitis and bacteremia, and is associated with a longer disease course and increased mortality. However, the early immunosuppression of SAP is often ignored in clinic, and the optimal time for treatment is missed, which leads to progressive aggravation of secondary infection. This article summarizes the researches of early immunosuppression SAP in recent years to provide reference for early identification of immunosuppression and timely immune intervention to reduce the infection complications at the early and late stages of the disease course and improve the prognosis of patients.