Based on analyzing the system and network characteristics of the railway financial analysis, it discusses the necessity of financial analysis based on network. Combining with a specific case, it analyses the related network, associated projects, with or without project and other key issues, then expounds the with or without project volume, identification and calculation of costs and benefits in detail. For cost calculation, it probes into construction investment estimate of this project, the associated investment estimate, operating costs, and other important issues. For benefits, it detailed analyses the increase of the number of transport products, improvement of transport quality and lower transportation costs three parts. Finally it concludes the necessity, objectivity and feasibility of network-based financial analysis in railway construction projects.