Serum alanine aminotransferase (ALT) is a biomarker of hepatocyte damage. However, the relationship between normal range of serum ALT level and metabolic syndrome (MetS) has not been completely understood. This study aimed to investigate the correlation between normal range of serum ALT level and MetS.A total of 2453 participants from the Beijing Community Pre-Diabetes study were enrolled. Multiple linear regression analysis was performed to calculate the regression coefficient. Normal serum ALT levels were divided into quartiles. Logistic regression model was used to compare the relative risk of MetS, and the receiver operating characteristic (ROC) curve to calculate the optimal ALT boundary value for predicting MetS.The frequency of MetS increased with the ALT level within the normal range. Compared with the first group, the risk of MetS was greater in the other quartiles of ALT level in males, the difference was significant for the fourth group. For females, the risk of MetS increased with ALT level within the normal range as well, with all differences showing statistical significance. The optimal ALT boundary value of the ROC curve for males and females was 24.5 and 14.5 U/L, respectively.ALT was related to metabolic factors and used as one of the indicators to assess the morbidity risk of metabolic diseases.