Abstract: The level of Tibetan economy and society has been improved remarkably since the reform and opening-up of China. But the population pressure of Tibet has increased as the same time. High natural growth rates in rural areas produces certain negative effects on urbanization and floating population become the main strength for speeding up the process of urbanization in the new era. At the base of talking about the effect of population growth and floating on urbanization, this article analysed the integrative characteristics of the change in urban structure of function, scale and space. It also pointed out that economic function became important factor to accelerate the expansion of urban scales in recent years and the new towns played an important role in Tibetan urbanization which made the spatial pattern of urban distribution become dispersion on the whole and local concentration. Furthermore, conflicts is discussed between population increase, urbanization, resources and environment, and social economy. Authors brought forward some standpoints: first,the convergence of population and industry makes the urban capacity towards gradual saturation; second,the competition for employment and restricted urban capacity brings great pressure on native farmers' urbanization; third, being held up of a great number of farmers in the land aggravated pressures on resources and environment; fourth, the shortage of construction funds influenced the improvement of urbanization quality, and urbanization process brings certain impacts on the protection and succession of Tibetan characteristic culture. At last, there is a brief conclusion that the sustainable urbanization is the goal which can be pulled off in the process of population development and urbanization in Tibet.