The past thirty years have witnessed rapid growth in internal migration in China. With the transformation in social and economic development mode in China，what are the new characteristics and trends of internal migration？The essay uses census data and dynamic population monitoring data to analyze the transition of size，structure and spatial distribution of China’s migrant population. The essay has several findings. The growth of migrant population has slowed down and entered a “slow lane.” Changes in population，economies and policies have brought more uncertainty. The structure of migration population has undergone the improvements in quality structure，ageing in age structure and differentiation among groups. The mode of migration has changed，and the appearance of “extended family” has led to the increase in family migration，highly skilled migrants and urban-urban migrants. The spatial distribution of migrant population has been diversified. Metropolitan region and coastal megalopolis in eastern regions have formed and the urban agglomeration in middle and western regions will become the new center of migration.