Paraneoplastic syndrome is a group of clinical symptoms and signs caused by malignant tumor disease, such as Cushing’s syndrome, hyponatremia, dermatomyositis, myasthenia gravis, and other disorders of the patient’s body hormone level, electrolyte balance, blood, nervous system, skin, etc. The cause of paraneoplastic syndrome is unknown. The etiology of paraneoplastic syndrome is unknown, and it may be a tumor-related syndrome caused by abnormal substances secreted by malignant tumors or abnormal autoimmune function. Clinically, the patient’s symptoms are quite diverse, generally with the effective control of the malignant tumor disease, these symptoms and signs will be reduced or disappear. At present, there is no specific treatment for paraneoplastic syndrome, and the treatment mainly focuses on controlling the primary malignant tumor, and if respiratory failure or epilepsy and other emergencies occur, symptomatic treatment should be given in time. It is recommended that patients should consult the doctor if they have any discomfort and take active treatment in order to avoid delaying the condition.