The invention provides a deicing control method for a wind turbine generator system. The deicing control method for the wind turbine generator system comprises the following steps that (a) data detected by a blade icing detection device are transmitted to a tower top control cabinet, so that whether blades are frozen or not is judged, and whether a deicing device is started or not is determined; (b) the tower top control cabinet analyses the icing degree according to the data detected by the blade icing detection device and determines the heating mode of the deicing device; (c) the tower top control cabinet transmits the determined heating mode to the deicing device, and the deicing device conducts the corresponding heating mode; and (d) the blade icing detection device conducts data refresh operation at intervals, judges whether heating is conducted or not again and determines the heating mode again. The invention further provides a deicing control system for the wind turbine generator system. The deicing control method and system for the wind turbine generator system can automatically detect whether the wind turbine generator system is frozen or not, conducts startup or stop operation on the whole system according to the set automatic control strategy, and improves the safety and the automatic operation performance of the wind turbine generator system.