A muscle biopsy is a pathological examination of a small amount of muscle tissue. There are many relevant pathological examinations that can be performed, such as simple smears or immunohistochemical examinations, in order to make a diagnosis of muscle disease. Pathological examination is the gold standard for all diagnoses, because it allows direct visualization of the degree of cell development, such as naïve cells, mature cells or cell heterogeneity, to determine the cause of tissue disease in a comprehensive manner. Therefore, muscle biopsy is the gold standard for the diagnosis of muscle diseases and is the final diagnosis. All the diagnoses made by doctors’ examination, imaging or blood tests are not as accurate as the pathological diagnosis. Therefore, muscle biopsy is the golden indicator for the diagnosis of muscle diseases and the most effective diagnostic method.