This paper discussed the spatial differentiation of the road accessibility under 〖JP2〗the effect of Beijing-Shanghai high-speed rail (HSR). Firstly measured accessibility changes in the spatial distribution of four different accessibility indicators, computed and mapped using a GIS support. The accessibility maps described both the possible benefits and their spatial distribution of the region. Subsequently measured the transport equity by calculating a set of inequality indices of the accessibility distribution and estimated whether the disparities in regional accessibility are increased after the implementation of the HSR. Finally we applied the GIS based technique to calculate the service population scale of every station. The results showed that the HSR obviously improve the overall road accessibility level, reducing greatly total travel time among the central cities. However, it leads to more polarized accessibility patterns of the spatial development which indicated that various regions obtain unbalanced accessibility gain from the HSR, establishing island or corridor spatial patterns with the highest lever accessibility which replaces the ellipse concentric circle shape of road accessibility spatial structure. In addition, the HSR contributes to enlarging the service market demarcation and broadening regional labor markets of main central cities along the line in short time distances and promote many urban agglomerations to facilitate co-operation. Moreover, the HSR stations become the rapid traffic network nodes and the hub of the social and economic activities.