The Urban system is a system that consists of some cities and these cities are different in scale and character and interact with each other. In the paper, the authors takes the study of the urban system in Northeast region for example and with the base of statistical figures, probes the ways to study the regional urban system quantitatively. The Northeast region is a relatively complete region, and the urban system in the region is relatively perfect, therefore the study method and results in the paper will be useful to the development of urban geography.