This article proposes a new segmentation algorithm which will be used in the field of GIS. It uses first Hash-Trie tree

two hash table manage the first word and the last word of a geo-item and the reaming words are built on Trie tree whose degree has decreased in that way

as the dictionary and based on an improved MM segmentation algorithm

deal with the ambiguity division and the unregistered words. The experiment indicates that the segmentation method can offer effective semantic information for the field of GIS about the understanding of Chinese query.