Frailty is defined as a syndrome of reserve and function decline caused by various reasons, and is associated with adverse outcomes, such as falls, depression, disability, mortality, and so on. There is no gold standard for frailty yet, but frailty assessment tools can help to screen frailty and predict the health outcomes. The frailty tools have wide application, and each frailty tool is targeted to a specified population. Thus, assessment of frailty in clinical practice can provide physicians strategies for early screening and management of diseases, so as to avoid or delay the adverse outcomes.