The invention relates to a data transmission method for a gateway and a smart substation monitoring system data center, and belongs to the technical field of electric power engineering relay protection automation. Virtual smart IEDs are constructed according to operating business services or subsystems of a sub-station monitoring system data center. The virtual smart IEDs are servers meeting the IEC61850 standard. The data transmitted to a master station are classified by the virtual smart IEDs according to functions. A logic node is constructed for each function for bearing function data, and interaction of the data and commands with the gateway is performed according to the IEC61850 standard. The virtual smart IEDs are constructed according to the operating business services or the subsystems of the sub-station monitoring system data center so that interaction between the sub-station data center and the gateway is performed by adopting an MMS message, and the gateway can transmit the data to the master station according to the requirements of the master station for the data. Reliability of a monitoring system is enhanced, pressure of rapid expansion of the data capacity of the master station is reduced, load carrying capacity of the system is enhanced and large amount of redundant data of the master station and sub-stations can be effectively utilized.