Joint pain caused by lung cancer usually manifests in finger joints, knee joints, ankle joints and other parts of the body, and the pain is more obvious and intense, but a single symptom cannot be carried out to judge whether it is lung cancer. Generally, lung cancer does not have joint pain, but if there is paraneoplastic syndrome, i.e. some active substances produced by tumor cells, which will trigger some symptoms in human body, joint pain may occur, and the pain is usually very obvious and intense. However, joint pain may also be rheumatoid arthritis, joint tumor and other diseases, not necessarily lung cancer. To diagnose lung cancer, we need to go to the hospital and combine the clinical symptoms with the doctor’s guidance, such as whether there is cough, chest tightness, shortness of breath, fever and other symptoms, and then we also need to carry out CT of chest and CT of joints, and if necessary, do pathological biopsy to make clear whether there is lung cancer or not. No matter what kind of disease is finally diagnosed, one should actively cooperate with professional doctors for treatment without delay, so as not to aggravate the condition.