The collaborative development of airports is an important part of integration of Beijing, Tianjin and Hebei province. The research of transportation accessibility of airports is one of the important measures and methods to clarify the scope of airport service and promote the coordinated development of the airports. Then we discuss the relation of airports transportation accessibility and population distribution, which has theoretical and practical significance to coordinated development of the airports in Jingjinji area. This paper calculates spatial accessibility of all airports in Jingjinji area using cost weighted distance method and ArcGIS 10.1 as platforms, and the hour circle of accessibility is divided to analyze the relationship of airports accessibility and population density distribution in different time circle. The inherent mechanism of distribution of different hour circle airport accessibility and population density is revealed to provide the scientific basis for the coordinated development and function position of airports. The result shows that: airports accessibility have the characteristic of high in the south, low in the north, middle area better than edge area in the Jingjinji region. The spatial distribution frequency of airport accessibility in the region presents the trend of inverted U type. Most of the airports accessibility is low and intermediate level in the Jingjinji area, it is urgent to improve the regional airport accessibility. The correlation of airport accessibility and population density is significant. With the increase of the percentage of airports accessibility, the percentage of population density decreases, the correlation coefficient is -0.73, the negative correlation can be quantitatively expressed by the power exponent equation. The 1.5-hour circle is the limited distance for the effects of airports accessibility on population density distribution. The correlation have a significant difference in the Beijing, Tianjin and Hebei province. In the Beijing and Hebei province, the main effect of airports transportation accessibility on population density distribution is 1-1.5 hour circle, in the Tianjin province, the main effect is 0.5-1 hour circle.