The optimized design of orifices in the electro-hydraulic control valve actuator will affect the response and the impact of valve in the camless engine, and thus affect all aspects performance of engine. The mathematical model of the orifices in the valve actuator was designed, and the effects of the orifice’s diameter to the velocity during opening and landing were analyzed. The model of the camless electro-hydraulic valve actuator was built by using AMESim, the analysis of the influence to the diameter and related position of the valve orifices was done, the results showed that the orifice diameter decreased or the related position of damping chamber orifice increased resulted in the delay of opening time, and the orifice diameter decreased or the related position of main line orifice decreased resulted in the delay of closing time. The parameters of orifices diameter and position were optimized, and the demand of the valve was met by the optimized parameters through the experiments.