The invention discloses a hybrid simulation method for an AC/DC power system, and the method comprises the steps: selecting an interface line of a simulation system, and dividing the simulation systeminto a large-step electromagnetic transient simulation system and a PSCAD/EMTDC simulation system according to an interface; establishing a simulation model for the AC/DC power system; performing simulation, wherein before the steady state is reached, the electrical connection between the alternating current system and the direct current system of the simulation model is disconnected through an isolation switch; after the direct-current system reaches a steady state, collecting system power flow errors on two sides of the interface; judging whether the system power flow errors on the two sides of the interface are lower than a preset threshold value or not, closing the isolation switch if so, and continuing simulation till fault simulation is completed; and outputting computing results. According to the hybrid simulation method of the alternating current and direct current power system, the detection speed can be improved, the background detection error rate is reduced, and the repeated recognition phenomenon is avoided. The invention further discloses a hybrid simulation device of the alternating-current and direct-current power system and a storage medium.