People can select the appropriate travel mode，based on travel costs，starting from their own travel expectations in the urban transport system. This article found by calculating that the cost of private transport is less than public travel，resulting in a large number of urban transportation resources occupied by private transport and an unreasonable allocation of resources. This paper argues that the government should adopt a long-term and short-term approach and a reasonable regulation of public travel costs for reducing traffic congestion，to achieve full optimization in city traffic，in order to respond to and prevent congestion from occurring.