Taken together, we identified that miR-338-3p expression was downregulated in osteosarcoma and that KLF9-miR-338-3p axis could inhibit the proliferation, migration as well as invasion of osteosarcoma cells through targeting NRCAM, which may aid to find a novel therapeutic target for osteosarcoma patients. The gene discussed is NRCAM; the disease is osteosarcoma.