Late life depression （LLD） has long been a challenge in clinical diagnosis and treatment due to its unique and complex nature in etiology， clinical features， assessment and diagnostic procedures， as well as treatment interventions. Centered on the core content of the Expert consensus on diagnosis and treatment of late life depression （2025 edition） and integrated with current clinical focuses， this article systematically interprets the consensus regarding its background， risk factors， feature identification and multidimensional assessment， diagnostic and differential principles， treatment strategies， as well as rehabilitation and recurrence prevention management of LLD. This article aims to deepen the understanding of the consensus， promote its application in clinical practice， and further elevate the level of standardized diagnosis and treatment of LLD in China. ［Funded by National Natural Science Foundation of China （number， 82171524）］