Uncertainty and fluctuation characteristics of wind power will intensify contradiction to power grid security operation. This paper proposes a systematic method to assess adequacy indexes of power system containing wind farms，which is based on scenario method. In order to have good approximation of wind power variation，a reliability assessment model is established based on the Latin hypercube sampling(LHS) and Simultaneous backward reduction(SBR) technique.The model take into account both the forced outage rate of traditional units and wind turbines and contains three typical scenarios for the output of the wind turbine, the conventional unit and the load, which provides support for adequacy evaluation for power system containing wind farm at all stages. On the basis of the preliminary work, the paper proposses a calculation method for adequacy indexes of electric power supply and peak-load regulation demand, which has?certain?rationality?and?feasibility. This paper introduces a concept of Equilibrium Point which will provide guidance to determine the appropriate capacity of the wind power. At last the results on IEEE-RTS system with wind farms demonstrate that the proposed method is feasible and effective.