Muscle MRI is one of the five major adjuvant examinations for muscle disease and has a history of 20 years of clinical development. The study of muscle MRI was first carried out by Professor Chen Qingtang at Peking University First Hospital in 1987, led by Professor Wang Weiwei, and in recent years the study has been widely carried out in many hospitals in China and has developed rapidly, with many clinical studies in the international leading position. Muscle MRI is a non-invasive objective examination method with high medical economics value especially suitable for pediatric patients, taking this examination can make the diagnosis of diseases less complicated and save the overall cost. This technique analyzes the degree of edema and steatosis of different muscles to understand the distribution pattern of the affected muscle groups and the activity of the disease. The MRI examination of muscles has been performed in thousands of patients at North University Hospital, and has become a routine tool in the diagnosis of muscle disease, mainly for the following: Judgment of disease and prognosis, in general, the occurrence of muscle steatosis is irreversible damage to the disease, while the absence of steatosis there is the possibility of treatment, sometimes high creatine kinase is found, while there is no change in muscle MRI, this situation suggests that the disease is not serious In some cases, high creatine kinase is found without any change in muscle MRI, which suggests that the disease is not severe and no special treatment is needed. To guide the choice of muscle biopsy site, many muscle diseases have a muscle group selective pathology, one muscle is severely damaged while the next muscle may be completely normal, performing muscle MRI can increase the positive rate of muscle biopsy, but it cannot replace muscle biopsy. It assists in the analysis of the causative genes of hereditary muscle diseases, and is currently used mainly for the diagnosis of myotonic dystrophy and the observation of disease progression. It is more significant for the diagnosis of pseudohypertrophic myotonic dystrophy, limb-girdle myotonic dystrophy, collagen VI disease, myogenic fibrous myopathy, congenital myotonic dystrophy, and the significance of congenital myotonic dystrophy requires further analysis. The diagnosis of various inflammatory myopathies has a high reference value and is an indicator for the discontinuation of treatment of inflammatory myopathies. The edema disappears before the drug can be reduced to the minimum dose and discontinuation of treatment, and seeing the steatosis indicates that this part of the muscle damage cannot be treated.