Aiming at the problem of flow pulsation caused by large displacement of non-circular gear pump during the fluid transmission process， the optimization method combining ADAMS-Simulink co-simulation with computation fluid dynamics (CFD) numerical simulation was proposed to realize the smooth transmission of gear pump rotor and reduce its flow pulsation.The transmission characteristics of high-order elliptical gear rotor were analyzed,and the influence of eccentricity and order of gear on transmission ratio was discussed.The effect of eccentricity on flow pulsation was analyzed by taking ovoid gear rotor as an example.A co-simulation model based on Simulink and ADAMS was built.PID control was used to realize the smooth transmission of the ovoid gear pump rotor to achieve the purpose of cushioning and damping.CFD numerical simulation analysis of ovoid gear pump was carried out by using Fluent dynamic mesh technology.The data coupling between Fluent and Simulink was realized based on Visual Studio network programming platform.The relation of speed ratio with smooth transmission of the rotor was precisely simulated.The results show that the flow pulsation of the rotor is reduced by 30.72% after smooth transmission.The method can suppress the flow pulsation without changing the internal structure of the gear pump.It has a remarkable optimization effect.