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The aerodynamic loads of wind turbine blades are substantially affected by dynamic stall induced by the variations of the angle of attack of local airfoil sections. The purpose of the present study is to explore the effect of leading-edge protuberances on the fluctuation of the aerodynamic performances for wind turbine airfoil during dynamic stall. An experimental investigation is carried out by a direct force measurement technique employing force balance at a Reynolds number Re=2 × 105. The phase-averaged and instantaneous aerodynamic loads of the pitching airfoil, including the baseline and the wavy airfoil, are presented and analyzed. The phase-averaged results indicate that the effects of dynamic stall for the wavy airfoil can be delayed or minimized compared to the baseline airfoil, and the negative damping area of the wavy airfoil is significant decreased in full-stall condition. These effects of leading-edge protuberances are more notable at a higher reduced frequency. For the instantaneous aerodynamic loads of the wavy airfoil, there is an observable reduction in fluctuations compared with baseline case. Furthermore, spectral analysis is applied to quantitatively undercover the nonstationary features of the instantaneous aerodynamic loads. It is found that the leading edge protuberances can reduce the harmonics of the aerodynamic force signal, and enhance the stability of the aerodynamic loads under different reduced frequencies. In conclusion, leading-edge protuberances are found effective to reduce the fluctuation characteristics of the aerodynamic loads during the dynamic stall process, and help to improve the stability and prolong the service life of the wind turbine blades.