method of map bullding for indoor envlronment is prescntcd. It is based on adaptive clustering and welghted averaging, Different threshold valuc Is sclccted to cluster these sompling points at different posltion. Clastering with varlant threshold is more reasonable than It with constant threshold. Line segments are extracted from these sampling polnts and are used to approximate the shape of environment, Parametcrs of llne segment are computed with a welght vector. Line segmcnts in envlronmental map are arrangcd according to their geometric posilion relation. This type of map is more accurate and more useful for mobile rohot navigation. All there technlques have been implemented on our mobllc robot ATRVII equipped with 2D laser range scanner SICK.