Wind speed is of intermit and random characteristics. The uncertainty of wind speed variation directly causes the uncertainty of wind power generation. To deal with uncertain wind speeds and power generation， an interval model is built，and an uncertainty power flow analysis method is proposed. Taking one real wind farm in the Qingdao power grid as test system， the results verify the proposed model and algorithm， and prove that they are valuable and effective in studying the influence of wind power generation uncertainty on the steady state operation of power system.