To build a more efficient and multi-level public transportation system, effectively alleviate traffic congestion, significantly improve the quality of urban transportation services, and provide strong support for the sustainable development of Shanghai, an in-depth study on public transportation in the main urban area of Shanghai is carried out. The current development status of public transportation is analyzed in detail. The existing plans are systematically sorted out. The necessity of developing the medium-volume transit and its functional positioning are discussed deeply. A comprehensive and forward-looking overall planning scheme for the medium-volume transit network has been proposed. The effect evaluation shows that improving the medium-volume network can achieve the integration of the functions of the three networks, fully cover the passenger flow channels, significantly enhance the operational efficiency and service levels, and basically control the impact of social vehicles.