At present, clinical diagnosis of osteosarcoma in children is mainly judged by combining clinical symptoms and imaging examination. 1. Clinical symptoms, osteosarcoma occurs in proximal tibia, distal femur and proximal humerus epiphysis. Clinical symptoms can be manifested as localized persistent pain at the lesion site, especially aggravated at night, accompanied by localized lumps and limitation of movement of nearby joints. 2. Imaging examination, osteosarcoma can show different patterns on X-ray, and osteolytic, osteogenic and mixed bone destruction of dense bone and medullary cavity can be seen, meanwhile, periosteal reaction is more obvious. MRI (Magnetic Resonance Imaging) can be added if there are abnormalities in the X-ray. Clinical diagnosis of osteosarcoma is made through the above ways, if there are clinical manifestations such as bone pain and localized lumps, it is recommended to go to the hospital as soon as possible, and follow the doctor’s instructions to standardize the treatment, so as to avoid delaying the condition.