A method and apparatus for estimating a state of health (SOH) of a battery are provided. The method includes measuring a voltage and a partial discharge time of the battery, acquiring a normalized partial discharge time using a battery model of a reference battery normalized with respect to a time, calculating a full discharge time of the battery based on the partial discharge time and the normalized partial discharge time, and estimating the SOH based on a ratio between a stored full discharge time of the reference battery and the full discharge time of the battery.