Abstract: Population is an important social and economic resource, and the aging population is gradually becoming an unavoidable problem in the sustainable development of Guizhou’s economy and society. Studying the differences of ageing population in different counties across Guizhou province can provide a scientific reference for the solution of aging problems and the rational formulation of population policies. The age coefficient of Guizhou county during 1990-2010 was selected as the indicator of population aging. The method that we selected to explore the characteristics of population aging and environmental causes were The spatial auto-correlation and hot-spot analysis, geographical weighted regression and partial least squares method. The article draws the following conclusions: (1) During 1990-2010，the age coefficient of the county in Guizhou province generally decreased from northeast to southwest. After 2000, the internal organization of the space was obvious. The change of Guizhou’s ageing coefficient is roughly divided by Guiyang, the east old age coefficient increases rapidly, and the west slowly. (2) The spatial agglomeration of the elderly population in Guizhou province has been continuously enhanced，and the differences between regions have gradually expanded. The age coefficient of low-low area is significant growing, and there is obvious diffusion and transfer of cold hot-spot space.(3) There are spatial differences in the effects of environmental causes on population ageing. Precipitation in general is the main natural factor that promotes the gathering of the elderly population. Degree of terrain and temperature have negative effects on population aging. The influence of the improvement of rock desertification on population aging is becoming more and more stronger.