The invention provides a method, device and system for determining windward angle deviation and correcting windward angles. The method for determining the windward angle deviation comprises the stepsthat historical running data of a wind generating set within a specific time period are acquired, wherein the historical running data comprise environment wind speed values, measured values of the windward angles and output power values at different time points in the specific time period; and for any wind speed segment, based on the fact that the environment wind speed values in the specific timeperiod belong to the measured values of the windward angles and the output power values at the time points of the any wind speed period, the windward angle deviation value of any wind speed segment is determined. By means of the embodiment, the deviation existing in the measured values of the windward angles of the wind generating set can be conveniently and effectively determined.