Abstarct: Private cars are the first choice of citizens for urban trips because of their advantages compared to public transportation. The most important features of public transportation, that characterize their quality, are minimizing waiting and in-vehicle travel times and avoiding the need to change the route where possible. Transit Network Design and Frequency Setting Problem (TNDFSP) is a multi-objective optimization problem in which the routes of the public transportation network are determined by considering operational constraints. It is necessary for these routes to improve the efficiency of the network from passengers’ perspective while minimizing the operator cost. In this study, an optimization algorithm baxsed on cuckoo search algorithm was proposed to solve TNDFSP. In the first part of the study, perator cost included the number of vehicles required to operate on the network and users' costs consisted of waiting time, in-vehicle travel time and number of transfers. Results were compared on the basis of Mandl’s network as an accepted benchmark network in the relevant literature. Another objective function was formulated in the second part of the study incorporated sustainable design objectives. To address this issue a limited number of emission-free (electric) buses were considerd as a part of the fleet. The comparison of the results with similar pervious studies and optimization of the objective functions indicated the Cuckoo Search (CS) baxsed algorithm had a good performance in finding the optimal routes for the urban bus network regarding the objectives considered in this study.