Abstract: Some limitations exist in the traditional methods of measuring accessibility, such as lacking comprehensive and comparative analysis from various aspects. Therefore, in this study,the evaluation of accessibility is conducted with three indicators, i.e. weighted average me,economic potential, and accessibility gravity center. After the evaluation, dynamic changes of urban accessibility with and without high- speed rail (HSR) are analyzed by ArcGIS method.Then comprehensive variable coefficient, hierarchy analysis and improved Huff model are used to nalyze spatial evolution characteristics and regularity of cities and regions along the HSR. Finally, the comprehensive accessibility of various HSR lines (nine HSR lines are involved in this study) is evaluated with Entropy-weight method, based on the accessibility system which is nstructed with six indicators, i.e. Ai, Pi, Ci, D- Value, CV and Pij. Results show that the comprehensive accessibility of various HSR lines is ifferent, with the order of their comprehensive strength as follows: Beijing- Guangzhou > Beijing- Shanghai > Shanghai- Kunming > Hangzhou-Shenzhen > Shanghai-Chengdu > Harbin-Dalian > Qingdao-Taiyuan > Zhengzhou- Xi'an > Lanzhou- Urumqi. The accessibility shows a decreasing trend from the eastern and central regions via the northeastern region to the western region. The accessibility of vertical HSR lines is better than the horizontal HSR lines. The increasing rate of economic potential is significantly higher than the decreasing rate of weighted average travel time. The movement of accessibility gravity center results in the spreading and overlapping of different time circles. The HSR spatial linkage mode of "core- core" has gradually developed into the mode of "core- network". "Four national service centers", i.e. Shanghai, Beijing, uangzhou and Shenzhen, and "six large regional service centers", i.e. Tianjin, Wuhan, Chongqing,Nanjing, Hangzhou and Shenyang have emerged in the HSR network and "multi-center" HSR service patterns and increasingly complicated spatial clusters have been formed. Affected by the HSR network, the gradual change and remodeling of regional spatial pattern have become more and more complicated. Spatial pattern in the "T-shaped" axes presents an evolving trend of polarization to equilibrium and intercity flows accelerate the process of spatial integration.

Key words: accessibility, spatial pattern, four vertical and four horizontal lines, HSR network, comprehensive evaluation, China