The invention discloses a seamless switching method for an inverter power supply and a diesel engine set of virtual diesel engine control. The seamless switching method comprises virtual diesel generator control of the inverter power supply and seamless switch with the diesel engine set. The inverter power supply imports a diesel generator speed regulation link, a rotor motion equation and an excitation model based on droop control, and a second-order electromechanical transient model of the generator is adopted, so that the inverter power supply has similar electrical properties, mechanical properties and droop properties with the diesel generator, and an output voltage of the power supply accurately reflects an instruction voltage signal by double closed loop control. The inverter power supply adopts pre-synchronization control, so that the inverter power supply and the diesel generator output the same phase, and the seamless switch of the inverter power supply and the diesel generator is realized. The seamless switching method disclosed by the invention can be applied to the field of inverter power supplies, the field of new energy micro-grids and the like, and the application requirements of parallel connection of multiple converters or the parallel connection with the diesel generator can be satisfied.