Variable valve timing technologies for internal combustion engines are used to improve power, torque, reduce emissions, and increase fuel efficiency. First, the paper presents a new electrohydraulic full variable valve actuator (FVVA) system which can control the seating velocity of engine valve flexibly. Second, based on the NSGA-II genetic algorithm, the paper outlines a multi-objective optimization strategy and designs the parameters of the FVVA system to make the system easier to implement. Third, the paper builds the combined FVVA engine simulation model. The combined simulation and experimental results are executed to validate the designed FVVA engine. The simulation results show that brake power is improved between 1.31% and 4.48% and the torque is improved by 1.32–4.47%. Brake thermal efficiency and volumetric efficiency also show improvement. Experimental results have good agreement with the simulation results. The research results can provide a basis for engine modification design.