The invention provides an RLC load simulation system for preventing island detection, and a control method of the RLC load simulation system. The system comprises an energy feedback unit, a load characteristic simulation unit, a control module, and a control platform. An AC end of the energy feedback unit is connected to an AC power grid, and a DC end of the energy feedback unit and the load characteristic simulation unit share a DC bus. An AC end of the load characteristic simulation unit is connected with a grid-connected inverter, and then is connected to the AC power grid. The control module receives an instruction of the control platform, and transmits the instruction to the energy feedback unit and the load characteristic simulation unit. The energy feedback unit carries out the pulse width modulation rectification of a power grid voltage according to the instruction of the control platform. The load characteristic simulation unit selects the working mode according to the instruction of the control platform. According to the technical scheme of the invention, the energy is transmitted to the load characteristic simulation unit from an EUT, and then is fed back by the energy feedback unit to the power grid, thereby saving an energy consumption resistor in a conventional RLC island prevention load device, and saving a large amount of electric energy, so the system is greenand environment friendly.