Objective This study investigated the regenerative repair function of the juvenile heart by analyzing differential proteins found in cardiac fibroblast-derived exosomes in neonatal rats and adult rats. The aim of this research was to identify possible therapeutic targets at the molecular level following myocardial damage. Methods We isolated exosomes from neonatal and adult rat cardiac fibroblasts and extracted proteins for analysis using HPLC and LC-MS/MS. We identified differentially expressed proteins and further analyzed their gene ontology（GO）and Kyoto Encyclopedia of Genes and Genomes（KEGG）pathways using the DAVID database. To identify key genes，we conducted a protein interaction network（PPI）analysis using the STRING database and Cytoscape software. Re⁃ sults In neonatal rats，a total of 241 differentially expressed proteins were identified，with 117 up-regulated and 124 down-regulated. The GO analysis showed that the up-regulated genes were mostly involved in integrin-mediated signalling pathways and responses to hypoxia. On the other hand，the down-regulated genes were involved in negative regulation of endopeptidase activity. The KEGG analysis indicated that the up-regulated genes were mainly enriched in the Hippo signaling pathway，while the down-regulated genes were primarily involved in ECM-receptor interaction. PPI analysis revealed that one key gene（Rp17a）was up-regulated，while six key genes（Lamc1，Agrn，Itih3，Tfrc，Bgn and Atp5pd）were down-regulated. Conclusions In this study，proteomics and bioinformatics techniques were employed to identify differential proteins in exosomes derived from cardiac fibroblasts of neonatal and adult rats. The study also investigated the associated signaling pathways and key genes，which could serve as potential targets for precise treatment of myocardial damage.