Batrachium Pekinense L.Liou is the primary protection plant and the endemic rare plant of Beijing,whose growth needs high water quality.Protection measures like establishing nature reserves and tourist attractions are the first choice to protect the native habitats of rare plants.This study chose the Beijing Songshan national nature reserve and the adjacent Yudushan regional nature reserve as research area,surveyed the growth and distribution of Batrachium Pekinense L.Liou and its habitat features including hydrological characteristics,water quality and aquatic microbial community diversity to reveal the environmental factors that affect Batrachium Pekinense L.Liou's distribution in the nature reserves.Results indicated that the content of total organic carbon and the width of streams were the key environmental factors influencing the distribution of the Batrachium Pekinense L.Liou in the nature reserves.It suggested that we should facilitate the accumulation of bed mud,enhance water quality management and properly widen streams to provide much more organic matters and living space for the Batrachium Pekinense L.Liou.Our study provided scientific data for the protection of the Batrachium Pekinense L.Liou in nature reserves,which had great practical implications.