Abstract: Targeting to further improve the fuel economy of the city bus with power-split hydraulic hybrid powertrain operating under urban cycle, and take advantage the high power density of hydraulic hybrid fully, a kind of improved rule-based control strategy was proposed. Mathematic model was setup in Matlab/Simulink to investigate adaptive ability, effectiveness of rule-based control strategy was applied on the city bus with designed hybrid powertrain. The simulation results showed: with proposed hybrid powertrain, adopting power management of rule-based method, 23.4% improvement on fuel economy can be achieved.