To further verify the function of miR-140-5p in clinical samples, qRT-PCR and immunohistochemistry were used to detect miR-140-5p and the expression of HMGN5 and BECN-1 expression was detected in tissues from 15 cases of patients with relapsed osteosarcoma by immunohistochemistry (chemoresistant) and 15 cases of chemosensitive patients. The gene discussed is BECN1; the disease is osteosarcoma.