The invention provides a digital substation electric energy quality monitoring system which comprises an electronic transformer, a combining unit, an electric energy quality monitoring device, an electric energy quality management platform and a synchronous function unit which are connected in sequence, wherein the synchronous function unit is connected with the electronic transformer and the combining unit; the electronic transformer is mainly used for completing data acquisition and digital-analog conversion functions; the electronic transformer is mainly used for completing data processingand data transmission; the electric energy quality monitoring device is mainly used for completing electric energy quality data processing based on IEC 61000-4-30 and modeling of the data according toIEC 61850-7; the synchronous function unit is mainly used for completing data sampling rate setup and synchronization functions; the electric energy quality management platform is mainly used for completing electric energy information publishing. By adopting the system, different layers of devices of a digital substation can be covered, and a solving scheme for meeting a high digital substation sampling rate and a settable homological sampling rate is provided.