This case report described an application of comprehensive geriatric assessment (CGA) on a mild cognitive impaired case with multiple chronic diseases. The author provided nursing care and gathered information by observation, interview, listening, and home visiting from September 16, 2015 to January 13, 2016. Based on CGA, the author identified patient's health problems as follows: (1) chronic disease self-management deficit and poor medication adherence; (2) nutrition imbalance due to excessive intake more than body requirement; (3) reduced social activities, and increased the risk of falling. The author provided appropriate nursing interventions to patient and helped to keep his basic activities of daily living and functional ability, then prevented and reduced the level of frailty.