Abstract: The 21st century is a century of urbanization. Both townie regionalism and regional urbanism are inevitable outcomes of improvement of the urbanization. Interaction of the city and region is the direct motive forces that town's regionalism and regional urbanism. It plays important role in the " five balanced aspects " to balance development among regions and to balance urban and rural developments, which indicates balancing development between regions and cities becomes a urgent requirement in the social economic development and reformation of future China. Probing into the interaction mechanism between city and region is an important theoritical and practical subject demanding immediate solution, and it will solve the urban and regional problems, promote development of the city and region, improve the overall competitiveness of the city and region. For better complimentary interaction between city and region, this study focuses on effects on city and region by various mechanisms, so as to provide a scientific reference for solving urban and regional development problems and enhancing their overall strength.