The invention provides a power system hybrid simulation fault unified processing method. The method includes the following steps that: A, in hybrid simulation, a power system alternating current network is established at an electromechanical transient side through utilizing an electromechanical transient super real-time simulation program TH-STBLT; B, at a fault port, the power system alternating current network is divided into a normal sub network and multi-port fault sub networks; C, in the normal sub network, a power grid part is described through adopting a fundamental wave three-sequence network, and primary equipment dynamic elements such as a generator, a dynamic load and a power electronic device are connected into a positive sequence network; and D, in the multi-port fault sub networks, fault models of power system network elements are established according to fault information, and a multi-port and multi-fault complex admittance unified module Yf is derived; E, the Yf is superimposed into an admittance module Y of the positive sequence network of the normal sub network, and positive sequence voltage and positive sequence current of a fault port of the positive sequence network are calculated; and F, the voltage of the fault ports of a negative sequence network and a zero sequence network is calculated through the current of the fault port of the positive sequence network.