With the expansion of urban area, urban bus transit plays an increasing important role in urban transportation. Nowadays, factors for bus route network planning become increasingly complicated with the construction of rail transit in metropolises of China. The object of this research is to optimize bus network in Wuhan using a GIS-based framework to alleviate or solve the problems exposed from current existing bus routes in the city, such as reducing the route overlapping, enlarging the network coverage, and reducing the nonlinear coefficient. This research employs a method for multi-modal transit route design based on stops, which treats certain rail routes as restrictions. Genetic algorithm (GA) is applied to search for optimal combination of candidate routes. With the case of central area in Wuhan, a scenario has been developed for the short-term situation with No.1, 2 and 4 rail routes. A comparison is made between the existing and the optimized results. It has been found that our GIS-based optimization approach may generate more appropriate bus route network for the large city.