Music therapy is a non-pharmacological treatment tool in medical therapy, a relatively new therapeutic technique that has been proven to have an important role in the treatment of chronic diseases in the elderly at home and abroad. Through applying music therapy to the treatment of elderly patients with chronic diseases, patients could benefit from physiological, psychological and social aspects. Thus, it could help patients relieve pain, reduce the level of anxiety, improve the immunity of the body and increase comfort, keep a stable situation, which speed up the process of treatment of elderly chronic diseases. This paper mainly focuses on the principles of music therapy and describe some application of music therapy that already applied to the treatment of elderly patients with chronic diseases.