Dermatomyositis is a common type of connective tissue disease. In addition to the manifestations of dermatitis and myopathy, patients with dermatomyositis often result in the formation of secondary interstitial pneumonia, the incidence of which is high. Pulmonary fibrosis and honeycomb lung formation can occur in severe cases, when lung function is significantly reduced. Dermatomyositis combined with interstitial pneumonia has a poor prognosis, so for secondary interstitial pneumonia, early oral prednisone is needed, together with immunosuppressive therapy, to control dermatomyositis and interstitial pneumonia to improve the prognosis.