This study is an attempt to investigate functions of Abhar city as a medium sized city in Zanjan province spatial development structure. The method of this study is descriptive-analytical. Some quantity models and methods are used in study of the role of this city and its hinterland. The economical models represent that، this city has basic conditions in the second and third economical activities. Not only it has a proper growth in industry، but also it has an important service role. The study of hinterland shows that vast parts of services are allocated in its hinterland. It can be inferred from this study that without Abhar there would be a non equilibrium of spatial in network of province cities. The population models show this city has high elasticity index in province. Because of these advantages، Abhar has a basic role as the industrial and service center of settlements of the Eastern and South Eastern of Zanjan province based on the regional classification