Domestic and foreign scholars has extensively and deeply researched into plug-in hybrid electric vehicle's energy management strategies, and good results of energy saving and emission reduction has been achieved. In order to further improve the performance of plug-in hybrid electric vehicle, it is necessary to summarize the research status of its energy management strategies and analyze its development trend. Firstly, we summarized and analyzed the power source's energy flow distribution method of plug-in hybrid electric vehicle, and then pointed out two problems that needed to be solved in the current plug-in hybrid electric vehicle's energy management strategies. The first problem is the influence of engine coolant temperature and catalytic converter temperature on fuel consumption and emission isn't considered, and the second one is the current energy management strategies only take drive power demand as input and the cab cooling/heating power demand is ignored. Finally, two future research directions were proposed. The first direction is the energy management strategy integrating engine coolant temperature and ternary catalytic converter temperature, and the second one is the strategy integrating cab's cooling/heating power demand.