Close relationship of the ageing characters of residual life function(RLF) to that of life function is expounded and the characters of mean residual life function(MRLF) is given.

阐述了剩余寿命函数（RLF）年龄特性与寿命函数年龄特性的密切关系；给出了平均剩余寿命函数（MRLF）的特征；