The invention belongs to the application field of power electronic devices in a power distribution network, and particularly relates to a modeling method for a three-terminal flexible ring network device based on scheduling. The modeling method is characterized in that three power distribution networks are connected into a ring network by applying the three-terminal flexible ring network device, and control for active power and reactive power of a device port is realized; a power scheduling is drawn by adopting a method of fixed system voltage, power scheduling regions of a rectification terminal and an inversion terminal are acquired, then a power scheduling region required in engineering practice is acquired through an idealized model, and a power scheduling method for the three-terminal flexible ring network device with comprehensive security boundary conditions being considered is established. The modeling method provided by the invention provides a theoretical basis for power scheduling of the three-terminal flexible ring network device. It can be seen from a simulation result that the modeling method can provide an effective power scheduling region for the three-terminal flexible ring network device.