Chronic obstructive pulmonary disease (COPD) is one of the most prevalent diseases of the respiratory system in the elderly, and it poses a grave threat to the survival and quality of life. Examining the pathogenesis of COPD is extremely important for COPD prevention and treatment. To date, however, there is no medication for chronic obstructive pulmonary disease that can delay the lung function decline over time. According to studies, vitamin D offers new hope for the treatment of COPD. A deficiency in vitamin D can exacerbate the progression of COPD, whereas adequate vitamin D has a therapeutic effect on COPD. This paper summarizes the relevant domestic and international research, discusses the possible mechanism of vitamin D’s effect on COPD, and investigates the role of vitamin D, particularly in COPD patients.