概数助词“许”出现于上古汉语晚期,魏晋六朝以及隋唐五代时期为上升发展期,宋元开始走下坡路,明代开始走向衰落,大致于现代汉语早期在口语中消亡。这种演变轨迹,是概数助词“许”使用频率、语体分布、语义表达类型和组配能力等指标在不同历史时期动态变化的综合反映。概数助词“许”衰落的动因有三:一是“许”作为一个文言词,不能适应唐宋以来白话文学的表达需求;二是概数表达系统的新成员逐渐挤压了概数助词“许”的生存空间;三是“许”常跟其他概数表达方式共现,影响乃至弱化了人们对概数助词“许”的认可度。 The suffix “Xu” appeared in the late Middle Ages of ancient China. During the Wei, Jin and the Six Dynasties and the Sui, Tang and Five Dynasties, the Song and Yuan dynasties started to decline. The Ming dynasty started to decline, roughly disappearing in colloquialism in early modern China. This evolutionary trajectory is a comprehensive reflection of the dynamic changes of the indicators such as the number of auxiliary particles “Xu ” in different historical periods, such as the frequency of usage, the style distribution, the types of semantic expressions, and the ability of assembly. There are three motives for the decline of the number of auxiliary “Xu”: one is “Xu” as a classical Chinese word, which can not meet the demand of vernacular literature since the Tang and Song Dynasties; the other is that the new members of the system of approximate number gradually squeeze the “ ”Xu “ of the living space; third is ”Xu “ often with other ways of expression of the total number of congenial, affect and even weaken the people on the number of auxiliary ”Xu " recognition.