Abstract: To improve the level of service of public transit and implement transit priority in historic urban area,the average space of arterial road network was proposed aiming at the requirement of bus stop coverage.The bus travel process and average bus walking distance were analyzed on the basis of defining the average space of arterial road network.With respect to transit priority,the basic bus lines configuration required that the coverage of bus stops should be no less than 70% and 90% for the stations within the radius of 150m and 300m respectively.And corresponding average space for arterial road network was calculated.Combining with practical operability,the value of 300m was recommended as the average space of arterial network in historic urban area.The recommended value not only truly reflects the layout features of road network,but also improves the public transport accessibility in historic urban area.