Abstract: The correlation between population and economy and their changes are very important in the regional studies. Through the analysis of Population and GDP data in Gansu province during 1991-2010，based on the methods of geographic concentration，inconsistency index and Moran's Index，etc，their spatial differentiation and correlation are analyzed in Gansu Province. The following conclusions are found as follows：（1）The spatial distribution of geographic concentration of population and economy in the southeast is higher than that in the northwest. Those higher concentration areas are distributed around the cities and this trend is strengthening. （2）The geographical contact between population and economy is compact with a consistent geographic distribution，but there are some deviations between them. While the diversity of regional economy is reducing，the gap of population size is increasing. （3）According to inconsistency index，there are three types of relationships between population and economic development in the study area. The matching type of population and economy is changed from dispersive type to centralized one. The number of counties is changing in various types of region. The coordinated development area is constantly expanding. In generally，their relationship goes towards coordination. （4）According to the Pearson related index and spatial autocorrelation index，there is less temporal and spatial correlation between population and economy. And the corresponding relationships are changed from positive correlation to negative correlation. The number of counties is adding in the hot and swelling area. In other words，the area which has higher level of aggregation of population and economy is expanding. The spatial differentiation and association changes are affected by many factors，including the physical geography condition，the ecological and environmental quality，industrial structure，etc. On that basis，several tactics are put out of development of the northwest in Gansu Province.

Key words: population, economic, spatial variation, space correlation, Gansu Province