Abstract: Vortex generators（VGs） are commonly used on wind turbine blades to mitigate the effects of flow separation. However, the complexity and strong unsteadiness of VG flows for large and extremely thick inner airfoils bring great uncertainty to VG design and performance evaluation based on numerical simulation. In present paper, the effect of vortex generator parameters on the flow and aerodynamic performance on a 40% thick airfoil was studied experimentally in NF-3 low speed wind tunnel of Northwestern Polytechnical University. The results show that the vortex generators improve the flow separation on the 40% thick airfoil effectively.Among the design parameters, the height of vortex generator and the chord installation position have the greatest influence on the aerodynamics performance.