This paper studies a common traffic problem in China: a large number of bus lines share the same stop. In rush hours, a long queue of buses waiting to get into the stop, which causes a rise of bus delay and a drop of traffic capacity nearby. First, a cellular automaton model is proposed to simulate such traffic scenarios. Second, to re-designing such busy bus stops to enhance efficiency, some principles are proposed and evaluated by simulations. Finally, a specific design example is given