Based on the Matlab/Simulink simulation models, This research focused on the application of Pontryagin's Minimum Principle in the energy management design of plug-in hybrid electric bus. This paper offers brief introduction of Minimum Principle, definition of specific problem, realization of this principle in Matlab environment and the final comparison of the fuel cost among Minimum Principle-based strategy, deterministic rule-based strategy and fuzzy rule-based strategy. The result suggest that Minimum Principle owns more potential for saving fuel. Keywords-Matlab/Simulink ； HEV ； Energy Management Strategy；Minimum Principle. I.