By using the entropy method and four dimensions (population, economy, society and land), we build the composite index of urbanization that measure urban development level of five northwestern urban agglomerations from two aspects, pointintime and slotintime. Through the system clustering and standard deviation, we analyze regional differences in urban agglomerations and their dynamic evolution features. The findings are as follows: (a) Regional differences in urbanization of western urban agglomerations characterize of Utype distribution and the urbanization level of the node cities within can be divided into four grades; (b) Comprehensive urbanization development level and its four dimensions of western urban agglomerations are increasing;(c) Regional differences in urbanization of western urban agglomerations are expanding gradually, and through the four dimensional measurement, the regional difference of urbanization and land urbanization is more obvious.Accordingly, we can take measures to eliminate the level gap of the northwest urban agglomerations urbanization from four dimensions.

northwestern urban agglomeration; the measurment of urbanization development level; urbanization development level; regional economic development