Plug-in hybrid electric bus (PHEB) has become a hot spot for bus research due to its lower energy consumption and lower emissions,etc. For the complicated and transient driving conditions of city bus,how to minimize the energy consumption of the whole driving cycle by designing the real-time energy management strategy for PHEB is still a problem in the recent years. To solve this problem,an equivalent consumption minimization strategy (ECMS) based on particle swarm optimization (PSO) is proposed. The energy management strategy based on the optimization equivalent factor is proposed. Considering the engine frequently start-up problems at lower vehicle speed,the speed limits for engine start is introduced,and the equivalent factor and the speed of engine start of certain condition is offline optimized by PSO to obtain the PHEB application online real-time strategy. The simulation model of the vehicle is built by Matlab/Simulink. The presented method is verified by simulation and hardware in the loop (HIL) experiments. The results show that,the research strategy could achieve global optimization PHEB approximate energy management strategies under different initial SOC_s,the vehicle fuel economy increases by 8.5% comparing with the rule-based strategy.