As the parameters in the control strategy for the hybrid energy storage system（HESS）have definite influence on control effect，it is advisable to make quantitative analysis and parameter optimization for this influence.A mathematical model for the energy storage system is presented with the influence of self-discharge rate and charge-discharge efficiency taken into account.A novel index named coordinated response margin of supercapacitor storage state of charge is proposed on the basis of the control strategy for HESS based on the charge-discharge state of lithium battery.A parameter optimization model for HESS coordinated control based on lithium battery quantized life is developed by referring to the lithium battery life quantization model applicable to the actually irregular charge-discharge application.An example demonstrates that rational choice of HESS coordinated control parameters can prolong the lithium battery useful life，thus improving the overall performance of HESS.