Determinants on Population Distribution in Mountainous Areas of China: A Case Study of Bijie Based on GWR Model

China is a mountainous country with a large population in mountainous areas. Mountainous areas have the specific characters of population, environment, society and ethnicity, so population distribution in mountainous areas has specific determinants. Taking Bijie in Guizhou Province as a case, the paper analyzes the influences of environmental factors, economic and social factors on population density by town based on GWR model. Population density is very sensitive to spatial scale. Researches of microscopic scale are different from those of macroscopic scale, so the results we obtained may be different from the past. First, economic and social factors have larger impact on population density than natural factors as we take town as a basic unit. Second, altitude does not influence population density as obviously as slope, which shows that the altitude is not the main determinant any more in high-altitude areas. Moreover, GDP, urbanization, transportation condition and terrain condition have diminishing marginal effect on population density, whereas medical condition has increasing marginal effect on population density. Therefore, the development of economy, urbanization and transportation will reduce the constraints, and the improvement of medical condition will play an important role in optimizing population distribution.