In order to quantitatively analyze the spatial interaction among regions, a new approach on reconstruction of intercity spatial interactional model based on spatial traffic system accessibility was proposed in this paper. Multi-indicators were used to comprehensively measure urban quality instead of a single demographic or economic index. Time distance combined with traffic distance was made as the final distance instead of Euclidean distance. The coefficient of the model is modified considering the proportion of passenger quantity and freight capacity, and the shortest travel time and so on. And then an example of reconstruction of intercity gravity model in Shandong Province has been done. The results showed that Qingdao has the most comprehensive strength, while Jinan has the highest spatial interaction. Although the comprehensive development level of a city has a great influence on its radiation capacity, the accessibility of the transportation system between cities also plays a certain role. The results prove that traffic accessibility has a guide significance to the spatial interaction among regions, and the new model is fit for the actual than the older one. It is a reasonable and effective method to analysis and research the capability of spatial interaction among cities.