Inhibition of mTORC1 pathway may reduce serine and glycine contents in osteosarcoma cells. mTORC1/serine/glycine metabolic axis promotes osteosarcoma proliferation and antioxidant ability to environmental stress. Our findings showed a novel mechanism of mTORC1-mediated serine/glycine metabolism in osteosarcoma cells. The present findings will help to provide new opportunities for drug development in osteosarcoma clinical therapy.