Abstract: 　Objective　To investigate the clinical characteristics, diagnosis, and treatment of childhood hypomyopathic dermatomyositis complicated with interstitial lung disease and pneumomediastinum. Methods　One case of childhood hypomyopathic dermatomyositis complicated with interstitial lung disease and pneumomediastinum was retrospectively analyzed. The  related literatures were reviewed. Results　A 10 years and 11 months old female patient with facial enythema one month had shortness of breath after activities, muscle strength of Ⅴ level, normal muscular tension and typical skin rash. The creatine kinase level was slightly higher. The electromyography showed myogenic damage. The knee MRI showed that the soft tissue of the posterior bilateral femur had high signal of STIR sequence. The chest high resolution computed tomography (HRCT) showed interstitial lung disease and pneumomediastinum. Thus, hypomyopathic dermatomyositis complicated with interstitial lung disease and pneumomediastinum was clinically diagnosed. Finally, the patient died after a combination of anticoagulation and immunosuppressive therapies. Conclusions　The diagnosis of interstitial lung disease and pneumomediastinum should be suspected in the patients of hypomyopathic dermatomyositis with normal creatine kinase. The mortality of this disease is high. Pulmonary CT examination should be implemented promptly.