Atrial fibrillation (AF) is a prevalent clinical arrhythmia characterized by an irregular cardiac rhythm, increasing the risk of developing stroke and heart failure. In order to explore the potential role of serum indicators, the study employed a combination of targeted metabolomics and Tandem Mass Tag (TMT) based proteomics to examine metabolic characteristics and biomarkers in the serum of patients with AF. Furthermore, the verification of protein expressions with diagnostic significance for AF was conducted in patients of larger sample sizes by ELISA. Proteomics and metabolomics identified 174 differentially expressed proteins (DEPs) and 294 differentially metabolites (DMs) in AF patients, respectively. The clustering and functional enrichment analysis identified the complement and coagulation cascade as the primary pathway dysregulating DEPs. According to the integrated study, the most enriched proteomics and metabolomics pathways were platelet activation and cholesterol metabolism. lactate dehydrogenase A (LDHA), lactate dehydrogenase B (LDHB), and transgelin 2 (TAGLN2) were significantly expressed in AF patients, while plasminogen (PLG) was low. In conclusion, the current study found that platelet activation, cholesterol metabolism, and the complement and coagulation cascade pathways may affect AF progression. The study also showed that LDHA, LDHB, TAGLN2, and PLG may be potential AF biomarkers.