Based on the current situation of urbanization development in West China, this paper analyses main factors responsible for sluggish urbanization in West China as follows: impact of environment factor, impact of population quality and quantity, lagging of public product service, stagnancy of technological development, backwardness of slow growth, and rigidity of system building. And then this paper analyses the restriction mechanism of urbanization in West China: at the superficial level, the constraints of urbanization in West China arise from the shortage of capital; at the profound level, the backward culture contributes to the constraints of urbanization in West China. The thread of resolving restriction mechanism of urbanization in West China is put forward from system, economy and culture. On the basis of this thread, we construct the power system for the development of urbanization in West China. The power system for urbanization in West China should be propelled by "four forces", namely, pull of external forces, cohesive strength of regional market environment, expansion power inside countryside, traction of industrial structure adjustment. Innovation is the engine of impetus for urbanization in West China; spatial clustering and modernization of industry is the major driving force for urbanization; the government behaviour, driving of foreign investment, great projects and other forces are supplementary power. Via the main power, we should take the market as medium to achieve the role of power in promoting urbanization.