Metachromatic leukodystrophy (MLD) is a rare hereditary leukoencephalopathy caused by arylsulfatase A (ARSA) gene mutation. There are individual differences in the clinical manifestations and disease progression speed of MLD, but almost all patients will eventually have complete loss of motor and cognitive functions. Clinically, patients are divided into late infantile onset, juvenile onset and adult onset according to their age of onset and severity of illness. The clinical diagnosis of MLD includes progressive neurological regression and typical magnetic resonance imaging (MRI) findings. Its clinical manifestations are similar to many diseases, and it needs to be differentiated from other leukoencephalopathies and lysosomal storage diseases. There is no effective treatment for MLD. Hematopoietic stem cell transplantation or bone marrow transplantation, enzyme replacement therapy and gene therapy are the research hotspots of MLD treatment. At present, only symptomatic support treatment can be carried out for patients. Recent studies have found that intrathecal injection of recombinant human arylsulfatase A (rhASA) could delay the progress of the disease. Effective prenatal molecular diagnosis for MLD families is the main method to prevent the occurrence of MLD.