Abstract: Population is a complex system, and population migration is a typical issue that has long been a concern of complex systems science. Based on the data of inter-provincial bilateral migration between provinces in China from the last three censuses, a complexity exploration study was conducted. 1) regional population migration patterns and their evolution in China are verified. 2) Based on multilateral probability migration model, a quantitative study is conducted on the barriers to inter-provincial population migration in China. Regression analysis reveals fundamental elements that affect regional mobility barriers, which can explain about 60% of all migrations．The influence of geographical distance, development index of migration destination and origin, housing prices of migration destination and origin on regional migration is found to be significant. Finally, a comprehensive analysis of pushing and pulling forces of five hot migration destinations (Beijing, Shanghai, Guangdong, Zhejiang, and Jiangsu) is conducted, similarities and differences among these destinations are discussed．