Abstract: The changes in the distribution of population and economic are very important in the regional studies. Thanks to the help of population and GDP data of Red-triangle Economic Zone in 1998-2008, based on the methods of regional gravity center and geographic concentration index, the coupling characteristics of the population and the economy of Red-triangle Economic Zone is analyzed, and the economic zone has been divided into three types by coupling index. The following conclusions are found: (1) The gravity center of economic are located in the west direction of the geometric gravity center, and the gravity center of population are located in the SSW direction of the geometric gravity center of Red-triangle Economic Zone;(2) The degree of geography concentration of population and economic in the West is higher than it in the East; (3) The geography concentration index are high related between population and economic; (4) According to coupling index, the Red-triangle Economic Zone can be divided into three types of advance-economic type, the coordinate development type, lag-economic type.