In this paper, the stochastic optimization of a horizontal-axis composite wind turbine blade is performed. Wind energy has become widely popular in recent decades as an alternative source of energy and many studies have been devoted to finding an optimal wind turbine blade using deterministic optimization. However, the actual responses of the wind turbine blade such as power generation are affected by the stochastic nature of wind, uncertainties in material properties and modeling parameters, and so on. This can have an undesirable impact on the performance and reliability of blades, which demands the consideration of uncertainties during optimization. To this end, a surrogate-based stochastic optimization of a wind turbine blade considering the influence of randomness in wind speed on power generation was studied. A slight gain in average power over the baseline blade was obtained and it demonstrated the promise of the presented framework for the design of wind turbine blades.