Abstract: To reduce the complexity and increase the calculation speed for nonlinear model of high speed onoff solenoid valve, the energybased model reduction algorithm was used. Considering the multidomain coupling characteristic, the concept of subsystem activity index (SAI) was proposed to evaluate the contribution of the subsystems. The full model was established and reduced in Matlab/Simulink environment and validated by a testbench experiment. With the error less than ±5%, the model built in this paper is accurate for further study.