Osteosarcoma is the most frequent primary bone tumor. Staphylococcal nuclease domain-containing 1 (SND1) is a multifunctional protein that plays important roles in tumor development and progression. Overexpression of SND1 has been found in several malignancies, however, its expression and function in osteosarcoma is largely unknown. In the present study, we firstly examined the expression of SND1 in 12 pairs of osteosarcoma and healthy bones by immunoblotting and real time-PCR. The results revealed that osteosarcoma tissues expressed significantly high SND1 mRNA and protein expression compared to normal bone tissues. Next, we stably overexpressed SND1 ORF in MG-63 cells and further defined the biological function of SND1 in osteosarcoma by flow cytometry, cell proliferation and in vivo assays. We found that SND1 overexpression significantly promoted cell proliferation and tumor growth in vitro and in vivo. Furthermore, the non-targeted metabolic profiling, ELISA and luciferase reporter assays were performed on stable overexpressing cells and blood samples to elucidate the underlying mechanisms of SND1-mediated oncogenic features. The results revealed that SND1 increased the production of arachidonic acid PGE2.The serum PGE2 expression level had a significant positive association with the SND1 mRNA expression level in osteosarcoma tissues. The SND1 overexpression-stimulated cell proliferation was enhanced by exogenous addition of PGE2. Additionally, we found that SND1 upregulated PGE2 expression through the NF-κB/cyclooxygenase-2 (COX-2) pathway. In summary, our findings revealed the mechanisms of SND1 involvement in osteosarcoma tumor development, and support the targeting of SND1 as a new anti-tumor strategy for patients with osteosarcoma. In addition, SND1 may act as a potential biomarker of the therapeutic strategies utilizing COX-2 inhibitors.