Abstract: Based on SPSS software package and GIS technology, this paper makes a comprehensive assessment on the socio-economic development at county level, and reveals the characteristics and the laws of regional disparity about socio-economic development in China. Firstly, factors that mainly influence the social regional differentiations are socio-economic structure, economic level and population quality, their weights are respectively 29.168%, 27.844% and 16.942%. At the same time, the relativity among indexes, measuring regional socio-economic development, indicates that change of each factor can give rise to the change of other factors in the system, therefore, preserving the integrated coordination of each regional factor is the key to raise the synthetical level of regional development. Secondly, in the view of county scale, for the gap between the development degree of social structure and population quality is far smaller than economical gap makes the regional gap estimated by the method of synthetical index is clearly lower than that of economic development. It not only indicates that some fixed limitations would be existed if we weigh the gap of regional development merely with the economic index, but also shows the correctness and feasibility of the policy to reduce the gap of regional development by reducing the gap of regional social development and that of public service. Thirdly, the space disparity in the level of social synthetical development, existing in counties of China, displays the different characteristics compared to the provincial region. Seeing from the east-west aspect, 4 corridors clearly appears by turns, that is, from the Coastal Higher Corridor, the Beijing-Jiulong Lower Corridor, then to the Beijing-Guangzhou Higher Corridor,at last to the Middle-West China Lower Corridor. It is clearly different from the view of provincial scale which is divided 3 districts as the east, the middle and the west. While in the north-south aspect, there are 3 higher corridors (the north along boundary, the Changjiang River, the Nanning-Kunming Corridor) and the lower level districts between them. All these indicates that the north-south disparity is forming in China, particularly along the Long-Hai railway is a lower level corridor traversing the east-west in China. Coordinating development of the northern and southern regions should be caused highly recognition by the executive department. In addition, in the region or smaller scale, economic development decreases from the center area to the marginal area step by step. Fourthly, space distribution of socio-economic structure, economic level and population quality level takes on obvious disparities in representation and intensity in counties. Hence, adopting discriminate analysis method, this paper classifies counties into 5 categories by using the targets of socio-economic structure, economic level and population quality.