Abstract: For the transmission efficiency of some lines is insufficient under the natural distribution of power flow, this article provides a detailed analysis of the topology and working principle of the high-voltage phase shifting transformer, deduces its equivalent model, and conducts in-depth research on its power flow regulation theory and power improvement effect in a dual ended power supply system. The simulation results show that the active power flow regulation range at the end of the line is 90.19～1 524 MW. Finally, an equal proportion prototype is developed and a dual terminal power supply experimental platform is built for testing. The adjustment range of the experimental prototype for the active power at the end of the line was 24.86～214.83 W, which verifies the effectiveness and feasibility of the device.