Objective: The expression and clinical significance of Procalcitonin (PCT) and Aspartate transaminase (AST) in Neonatal hyperbilirubinemia (NHB) were analyzed. Methods: 86 full-term children with NHB admitted to our hospital from January 2022 to December 2024 were selected as the case group. Meanwhile, 86 healthy full-term newborns who underwent physical examination in our hospital during the same period were selected as the control group. The serum TSB level of NHB children was detected and divided into non-severe group, severe group and extremely severe group according to the degree of serum TSB elevation. The levels of serum PCT, AST and other liver function indexes were detected and compared between the control group and the case group, as well as the children with different disease degrees in the case group. To analyze the relationship between the level of serum PCT, AST and other liver function indexes and the level of serum TSB and the severity of the disease in NHB children. Receiver operating characteristic (ROC) curve was drawn to analyze the value of each index in evaluating the disease condition. Results: The levels of serum PCT, AST, Alanine aminotransferase (ALT) and Gamma-glutamyl transpeptidase (GGT) in case group were significantly higher than those in control group (P < 0.05). Compared with the non-severe group, the levels of PCT, AST, ALT and GGT in the extremely severe group and the severe group were significantly increased, and the levels of PCT, AST, ALT and GGT in the extremely severe group were significantly increased compared with the severe group (P < 0.05). Correlation analysis showed that the levels of serum PCT, AST, ALT and GGT in NHB children were positively correlated with the levels of serum TSB and the severity of the disease (r > 0, P < 0.05). the Receiver operating characteristic (ROC) curve was drawn, which showed that the serum PCT and AST alone and in combination with all indexes combined to evaluate the severity and extreme severity of NHB in children. The values of AUC were 0.812, 0.892, 0.921 and 0.969, respectively. The value of combined diagnosis was higher. Conclusion: Serum PCT and AST levels are highly expressed in children with NHB, which is positively correlated with serum TSB level and disease degree in children with NHB, and the combined detection of the two indexes can improve the value of evaluating the disease degree of children with NHB.