Idiopathic inflammatory myopathies are a group of autoimmune diseases characterized by inflammatory skeletal muscle lesions, of which myositis and dermatomyositis are the most common. It has the same characteristics as other connective tissue diseases, such as multisystem involvement, elevated inflammatory markers (sedimentation, C-reactive protein, platelets, etc.), and positive specific autoantibodies, etc. In addition, dermatomyositis is often accompanied by a characteristic rash, symmetric proximal muscle weakness of the extremities, laboratory tests suggesting elevated serum myosin, electromyography The laboratory tests indicate elevated serum myoenzymes, electromyography indicates myogenic damage, and muscle biopsy indicates infiltration of inflammatory cells in the muscle bundles and around the blood vessels. The following is a brief description of the main clinical features of dermatomyositis. The following is a brief description of the main clinical features of dermatomyositis: (1) systemic manifestations: insidious onset, malaise, weight loss, poor appetite, fever. (2) Skin manifestations: (1) Gottron’s sign: seen in 80% of patients, red or purplish papules, often covered with scales, with skin atrophy, capillary dilation, hyperpigmentation, mostly located on the extensor surfaces of joints; (2) periorbital rash: edematous purplish rash on the upper eyelid or periorbital area; (3) V-neck sign, shawl sign: red rash located on exposed parts of the body such as the front of the neck, chest, back of the shoulder (4) mechanic’s hand: hyperkeratosis, roughness and cracking of the palmar and lateral skin of the fingers; (5) calcium deposits: calcification of subcutaneous and soft tissues; 3. Other systemic damage: myalgia, muscle weakness; joint pain; interstitial lung disease; myocarditis, arrhythmia; dysphagia, acid reflux, abdominal distention; kidney damage, etc. Compared to other autoimmune diseases, dermatomyositis has a higher chance of developing tumors. Therefore, early diagnosis and treatment of dermatomyositis is particularly important. If any of these symptoms occur, it is recommended to seek medical attention. Patients who have been diagnosed with dermatomyositis should not be overly concerned, as the disease is not terminal and treatment is aimed at improving muscle strength, improving quality of life and preventing progression of the disease.