Abstract: To meet the increasingly stringent requirements of automobiles on execution components of control-by-wire system, a kind of high-power density moving coil linear actuator was proposed to directly drive the piston of the hydraulic pump, thereby realizing the direct-driving electro-hydrostatic actuator (DEHA) with servo control of the actuator volume, and effectively shortening the path of power transmission. A multidisciplinary simulation model of DEHA with electromagnetic, mechanical, hydraulic and control coupling was established, the algorithm based on sliding mode and active disturbance rejection control for direct-driving piston motion was designed, and the influence of structural parameters, such as the diameter of the ball seat of the check valve core, the diameter of the valve core ball, the spring rate, and the spring preload, on the performance of DEHA was analyzed. Taking the dynamic response time of DEHA as target, the structural parameters of the check valve were optimized by genetic algorithm. Simulation and experimental results verify the effectiveness of the DEHA built model and optimization: when the trajectory of the plunger is the typical operating condition with a frequency of 20 Hz and an amplitude of 5 mm, the response time of DEHA moving 20 mm is less than 0.2 s.