Amyotrophic lateral sclerosis (ALS) is a rare progressive neurodegenerative disease characterized by simultaneous involvement of upper and lower motor neurons. At present, its diagnosis mainly depends on electromyography and clinical evaluation, but both of them have limitations and subjectivity. In recent years, the application of magnetic resonance imaging (MRI) in ALS has attracted the attention of researchers. Many studies have shown that MRI can be helpful for the early diagnosis and condition evaluation of ALS. MRI may become an important auxiliary means for the diagnosis and treatment of ALS in the future.