Embodiments of the present invention provide a method and a device for detecting SOC of a battery. The method for detecting SOC of a battery includes: determining an initial SOC value of the battery according to a waiting time of the battery; calculating a current SOC value of the battery based on the initial SOC value and a current working current of the battery, denoting as a first SOC value. In embodiments of the present invention, the current of the battery is real-time measured and the SOC value of the battery is calculated by accumulating the current of the battery, in addition, the initial SOC value is calibrated by the waiting time, so that the error of the SOC detection result is reduced, thereby increasing accuracy of the SOC detection result.