The invention provides a power flow control device and method for a run-through power supply system converter type traction substation, and relates to the field of power supply of an AC electrical railway. The power flow control device comprises a transformer type traction substation and an electrical railway run-through power supply system, wherein the electrical railway run-through power supply system comprises a plurality of converter type traction substations, wherein the input end of the control device is connected with a traction feed current transformer and a traction bus voltage transformer of the converter type substation, and is connected with a traction feed current transformer and a traction bus voltage transformer of the transformer type substation through an optical fiber, and the output end of the control device is connected with an AC-DC-AC converter control end of the converter type substation. The control method comprises the following step of adjusting the power of the converter type substation within an allowable voltage range of a traction bus by taking the current, the voltage and the power data of the transformer type substation as references so that the converter type substation and the transformer type substation approach the target of a train load on a traction network according to capacity proportion distribution. The control device is mainly used for the electrical railway run-through power supply system.