Polymyositis and dermatomyositis are a heterogeneous group of diseases with diverse and individualized clinical manifestations, and treatment regimens should follow individualized principles. To date, glucocorticoids remain the drug of choice for the treatment of PM and DM, but there is no uniform standard for hormone usage, generally starting with a dose of prednisone 1-2 mg/kg/d (60-100 mg/d) or equivalent doses of other glucocorticoids. Symptoms often begin to improve within 1-4 weeks of administration, with maximum improvement taking about 1-6 months, with an average of 2-3 months. It is generally accepted that the higher dose of prednisone at the time of initial treatment should be continued until CK returns to normal and clinical muscle strength improves (usually 1-2 months), after which a gradual taper should be initiated. The reduction of the hormone should follow the principle of individualization, and some scholars advocate the gradual reduction of prednisone to a maintenance dose of 5-10 mg/d over 6-8 months, with at least one year of maintenance treatment in remission before considering discontinuation of the drug. If a relapse occurs too quickly, the dose must be increased again to control the disease. In patients with severe myopathy or with severe dysphagia, myocardial involvement, or progressive interstitial lung disease, methylprednisolone shock therapy may be added by methylprednisolone 800-1000 mg daily as an intravenous drip for 3 days.