This paper deals with the route planning of public transit in urban road network for regional evacuation in emergency. In the investigation, first, the public transit evacuation system is modeled by using a time-expanded network. Next, a discrete and dynamic network flow model to minimize the total evacuation time is established, which transforms the route planning problem into a mixed integer programming （MILP） one. Then, a heuristic ta- bu-based search algorithm is designed to find out a high-efficiency solution to the route planning. Finally, a case study is conducted for the central road network of Changchun City in China, and the difference between the accurate results obtained from CPLEX9.0 and the approximate ones obtained from the tabu-based search algorithm is re- vealed. Numerical results indicate that the proposed time-expanded network-based model effectively represents the dynamic property of public transit evacuation system, and that the tabu-based algorithm reaches a compromise between the solving efficiency and the accuracy.