A method, device and system for determining angle-to-wind deviation and correcting angle-to-wind; the method for determining angle-to-wind deviation comprises: obtaining historical operation data of a wind turbine group during a specific time period (S101); determining an angle-to-wind deviation value for each wind speed segment on the basis of the acquired historical operation data (S102); for any wind speed segment, determining the angle-to-wind deviation value on the basis of the actual angle-to-wind measurement value and the output power value of an environmental wind speed value at a time point within the specific time period.