Reynolds number is one of the main factors affecting the aerodynamic performance of airfoil with vortex generator. In order to study the influence of Reynolds number on the aerodynamic performance of airfoil with vortex generator， Wind tunnel pressure experiment of NACA4418 airfoil model was carried out. Both aerodynamic performance variation law with different Reynolds Numbers of airfoil with vortex generator and the characteristics of the flow field around the airfoil surface are investigated. Then the improvement effect of vortex generators' parameters on aerodynamic performance of airfoil was analyzed. With the increase of Reynolds number， the effect of increasing lift and reducing drag of vortex generator is gradually enhanced， the range of attack angle to restrain boundary layer separation is gradually increased， and the boundary layer separation position of airfoil with vortex generator is gradually moved backward. The vortex generators' optimal installation position with different heights locates at 20% chord of the airfoil suction surface， whose position is the best for increasing lift and reducing drag of airfoil. The effect of increasing lifting and reducing drag of 5 mm high vortex generator is better than that of 3 mm high vortex generator.