The auto regressive (AR) method is applied to build the model of wind speed in wind field，and with the model, the wind time-history is obtained. The Glauert method is used to calculate time-varying input load，such as the time histories of thrust and torque of the wind turbine under the condition of variational wind speed. Based on statistical analysis，the design loading spectrum and rain flow histogram of the loads are obtained. The effects of wheel blade parameters on the input load under the condition of variational wind speed are analyzed，and the average loads of thrust and torque are obviously affected by the pitch angle. When the pitch angle increases，the loads of thrust and torque both decrease，meanwhile the amplitude of thrust first increases then decreases，while the amplitude of torque decreases monotonously. The thrust is obviously affected by twist and attack angles of blade while the torque is less affected by the twist and attack angles of the blade. The results lay foundations for reliability design，load control of the wind turbine as well as the parameter optimum of the wheel blade aerofoil under the real wind condition.