Abstract: In order to study the effect of the increase of rotor diameter and the elevation of hub height of the upstream wind turbine on the aerodynamic performance of the downstream wind turbine,the three-dimensional flow fields around two tandem horizontal-axis wind turbines were simulated by using the computational fluid dynamics method. The influence mechanism of upstream wind turbine rotor diameter and hub height on the aerodynamic performance of the downstream wind turbine was explored. The results show that increasing the upstream turbine rotor diameter can reduce the output power and increase the thrust pulsation of the downstream wind turbine at low frequency including 1APF,2APF and 3APF. Besides,this can increase the fatigue load of the downstream wind turbine. With the increase of the distance between two wind turbines,the influence of increasing upstream turbine rotor diameter on the output power of wind turbine outside the 12D range can be ignored,and the fatigue load of wind turbine outside the 12D range still increases significantly at low frequency and 1APF. When the wind turbine is closed,raising the upstream turbine hub height can make the downstream wind turbine avoid part of the wake and significantly improve the output power of the downstream wind turbine,although a large alternating load can be induced when the blade in the one-period rotation process. When the distance between two turbines is relatively far,raising the upstream turbine hub height is beneficial to wake recovery. Furthermore,this can increase the output power and reduce the fatigue load of the downstream turbine.