Spatial interaction research mainly focuses on showing the interaction relationship between regions. However, classic urban interaction models such as gravity model can only compute symmetric result between two regions, paying no attention on much individual phenomenon during region evolution process. Since radiation model proposed in 2012 can simulate directional, asymmetric urban interaction with O-D result, we improved and applied the radiation model to simulate the population movement between 333 cities in China in 2000 and 2010 to construct directed weighted network of the cities interaction in terms of population, and then utilized indicators of complex network to estimate the development during the ten years and the developmental differences between regions. The conclusion of this research is that the interaction intensity between cities in China rises dramatically from 2000 to 2010, during which balanced regional development becomes a macroscopical trend, and now in China, the east develops better than the west, and the south develops faster than the north.