Clinically， hypothyroidism（ HM） is not uncommon， but sometimes it is difficult to be diagnosed. Careful medical history and proper blood test are helpful for clinical diagnosis of HM. Although electromyography is not specific， it is useful in assessing the degree of neuromuscular impairment. MRI and muscle biopsy are helpful for differential diagnosis. The prognosis of HM is good. Thyroid hormone replacement therapy is the key treatment. The therapeutic effect is also an important basis for diagnosing HM. This article reviews the pathogenesis， clinical manifestations， diagnosis and differential diagnosis， treatment and prognosis of HM.