Abstract: Hu et al. first proposed the systemic immune-inflammation index （SII） based on prognostic scoring of inflammation and immunity in 2014. The calculation formula is platelet count×neutrophil count/lymphocyte count, which is widely applied in clinical practice because it is non-invasive, easy to calculate and economical. Previous studies have shown that SII reflects the balance between host immunity and inflammatory status. High SII level can be utilized to predict poor outcome in malignancies, and it is correlated with the severity of some diseases. In this article, research progress on the predictive value of SII for the incidence and development of digestive system diseases was reviewed.