The present invention relates to a method and system for controlling charging of a battery supplying power to a hybrid electric vehicle according to a driving state. The method includes: detecting, by a sensor, a speed of the vehicle, generating, by a generator, power according to a driving state of the vehicle; controlling, by a controller, a charge to the battery using generated power of the power generator based on a signal of the vehicle speed detector; calculating, by the controller, an average vehicle speed for a set time; updating, by the controller, the average vehicle speed at an update period shorter than the set time; changing a state of charge (SOC) charging band, a charging reference of the battery, based on the average vehicle speed; and determining, by the controller whether to charge the battery according to a driving state based on the SOC charging band.