With the accelerated population aging in China, major depressive disorder in the elderly is getting serious. Subthreshold depression (StD), considered the “preclinical” stage of depression, could cause higher suicide risk, disease burden and functional impairment. Accurate identification and evaluation of StD has profound significance to improving the mental health of the elderly and achiev-ing healthy aging. This article reviewed the concept and assessment tools of StD in China and other countries, analyzed and compared the contents, assessment methods, and scopes of application of different tools, helping the clinicians to make appropriate choice.