This paper analyzes the spatial structure of Changsha,Zhuzhou and Xiangtan city group on urban grade scale and the interaction between towns.First,it chooses the population,eco-social resource and infrastructures as factors to divide Changsha,Zhuzhou and Xiangtan district into 4 scale grades and makes an investigation of the spatial distribution of different grades;then,according to the distance and scale grades,the study calculates the interaction between towns.Based on the above conclusion,this study presents some suggestions at last,that is,to locate or identify key towns according to the current situation;to develop traffic and culture,and create key towns in weak regions;to form a network of spatial structure and to promote the development as a whole.