The invention discloses a method and a device for comparing running errors of an optical current transformer and an electromagnetic current transformer in real time, which are suitable for an intelligent substation provided with the optical current transformer and the electromagnetic current transformer at the same time. The field running error of the optical current transformer is subjected to data storage and remote analysis by utilizing a real-time ratio of field running errors, so that a data basis is provided for analysis of the running error of the optical current transformer; and the field running error of the optical current transformer is monitored in real time, so that the accuracy and the reliability of electric energy metering of the intelligent substation are guaranteed. Therefore, a good application prospect is achieved.