A stochastic economic dispatch model， which can take into account the uncertain outputs of plug-in electric vehicles（PEVs） and wind generators， is developed. A simulation based approach is first employed to study the probability distributions of the charge/discharge behaviors of PEVs. The probability distribution of the wind power output is next derived based on the assumption that the wind speed follows the Rayleigh distribution. The mathematical expectations of the generation costs of wind generators and vehicle to grid（V2G） power sources are then derived analytically. The feasibility and efficiency of the developed stochastic economic dispatch model is demonstrated with the IEEE 118-bus test system.