Abstract: Based on factor analysis method and ARCVIEW technology, taking central Liaoning Urban Agglomeration as an example, this paper makes a comprehensive assessment on the socio-economic development at county level, and reveals the actual characteristics and evolving characteristics of spatial disparity of urban agglomeration from 2000 to 2005. The results are as follows. Firstly, factors that mainly influence the interior development differentiation of Central Liaoning Urban Agglomeration are economic scale, social development, and industrial structure. Their weighs are different, and the economic scale had changed from second factor to first one from 2000 to 2005, which indicates that these three factors are not in a harmonious condition and the economy scale had been the main factor to prompt the comprehensive development of the urban agglomeration. Secondly, at county level, estimated by indexes, the absolute differentiation of comprehensive development level is smaller than that of economic scale, social development and industrial structure. Thirdly, Shenyang City and Anshan City have been both centers of Central Liaoning Urban Agglomeration, and north-south disparity and east-west disparity are forming. Fourthly, variability of comprehensive development level of county is severe, and it shows north-south disparity. By and large, comprehensive development level of county decreases step by step from a central county to a marginal county in the administrative region of a city. Finally, most counties were not in the harmonious development condition, and the harmonious degrees of most counties had descended from 2000 to 2005.