Stochastic User Equilibrium (SUE) model is equivalent to the problem of Stochastic User Equilibrium, and the solution is unique, so SUE model could be applied to traffic diverging during highway expanding construction. In this paper, SUE model is used with the expanding construction of Tongji highway(G010). Firstly transverse interference and parameters of travel time are adjusted according to the actual situation. And then the linear growth rule is used to predict the current theory traffic, based on which we use SUE model to divert the traffic in Tongji highway(G010) during expanding construction. Through the comparison between the calculation results and the actual traffic, we have validated the reliability of the calculation results and the rationality of the model.