Abstract:[Objective] To analyze the core genes and functional pathways in the differential expression profile of osteosarcoma based on bioinformatics analysis. [Methods] In this study, two microarray datasets, including GSE11414 and GSE14359, from the gene expres- sion omnibus (GEO) database were used to screen differentially expressed genes (DEGs) between human osteosarcoma and osteoblasts sam- ples. The potential biological functions of DEGs were explored through the Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analyses. The Search Tool for the Retrieval of Interacting Genes (STRING) database and Cy- toscape software were used to further construct a protein-protein interaction network and screen core genes. Finally, the prognostic value of core genes in osteosarcoma was assessed using the Long-term Outcome and Gene Expression Profiling database of pan-cancers (LOGpc) database. [Results] There were 111 DEGs in GSE11414 and GSE14359, including 28 up-regulated and 83 down-regulated DEGs. Func- tional enrichment analysis showed that DEGs were mainly enriched in the extracellular matrix organization, integrin binding, glycosamino- glycan binding, collagen-containing extracellular matrix, p53 signaling pathway, and TGF-β signaling pathway. Ten core genes were ob- tained by protein-protein interaction network analysis. Recurrence-free survival analysis confirmed that high expression of THBS1 and IGFBP3 was associated with poor prognosis in patients with osteosarcoma. [Conclusion] In this study, the protein-protein interaction net- work of differential genes in osteosarcoma was constructed by bioinformatics analysis. The core genes closely related to the pathogenesis of osteosarcoma were explored, which may provide new prognostic markers and therapeutic targets for osteosarcoma.