The connected effect of cities based on high-speed rail (HSR) is changing the spatial patterns of regional development.However, it needs to be proved through practice whether development can be achieved by building HSR.This paper focuses on cities along the "Harbin-Dalian" railway, and built triple difference evaluation model, associating information extracted from the train schedule provided by Qunar.com.Results indicate:the HSR greatly accelerates the connected effect between large cities; large cities exhibit accessibility effect on the surrounding cities due to the asymmetry of the HSR accessibility capacity, showing "polarization axis" characterization along the Ha-Da HSR.This work reviews the developing trend of the northeast urban belt, explains the influences on the cities from the HSR operations based on the examination of the HSR accessibility effect and the city connecting effect, and looks at the impact of the accessibility effect on the developing trend of the cities equipped with HSR.