Based on the basic principle of 6~10KV line over-current protection, design the on-site simulation realization under laboratory conditions and the simulation realization on the Multisim software platform. In the laboratory field simulation design, the principle wiring diagram-expand the wiring diagram-the design idea of the experimental wiring diagram, equipment selection and connection, a detailed equipment list and operation process, and finally recorded experimental simulation data. In the simulation design of the Multisim software platform, the field simulation experimental wiring diagram is the design basis Design the simulation circuit, and the equipment selection focuses on the presentation of functions. The connection structure of the equipment can be adjusted appropriately without affecting the actual function, and the simulation can be carried out in accordance with the on-site simulation operation sequence.The realization of virtual simulation must be based on the laboratory simulation data, and the two cooperate with each other , Learn from each other to achieve better teaching and learning results.