In view of the actual situation of different attributes of traffic travel behaviors,a continuous transporta- tion network design problem on the basis of stochastic equilibrium assignment is investigated according to the theory of the bi-level programming in network design.By synthetically considering the accessibility of road network and the equilibrium traffic assignment of stochastic users,a bi-level programming model is constructed,and the impor- tance of the node is introduced into the accessibility of road network.The lower level programming uses the La- grange multiplier method to solve the problem.Meanwhile,a particle swarm optimization algorithm is designed for the upper level programming,and the programming calculation is conducted on MATLAB.In a practical example,the road saturation is selected to verify the effect of expanded traffic networks.The results show that the constructed model is practical,and it can improve the road utilization of traffic networks and effectively solve the traffic conges- tion,thus decreasing the network average saturation by 28. 4%.