The invention relates to a simulated power flow calculation method for a transformer substation, and belongs to the technical field of operation and control of power systems. The method comprises the following steps: firstly, reading primary equipment information and topological relationship information in the transformer substation; secondly, generating topological island information according to the primary equipment information and the topological relationship; and finally calculating power flow data of primary equipment in topological islands according to power balance. According to the simulated power flow calculation method for the transformer substation, the connection mode and the operation mode of a bus are identified; the power, the power factors and phase current of various lines in the island are calculated in each topological island according to the power balance and the topological connection relationship of the transformer substation; a corresponding calculation is also carried out on the power flow under the operation modes of a bus coupler operation, a paralleling operation of a primary transformer and the like; the simulated power flow calculation method conforms to the power flow data characteristics of the transformer substation; and the power flow data are provided for a transformer substation monitoring system or a simulation training system.