During the operation of the power system, when a large load is suddenly lost and exceeds generator adjust capability, the frequency increases, meanwhile the frequency and power oscillate or even cause power system collapsing. In the isolation grid power system with only a few generators, the regulation capacity of the generators is limited, and the conventional load need serve as production tasks and cannot participate in frequency control. The isolation grid system lacks effective frequency control method. An electronic load device based on thyristor control is proposed, and the working principal of the device and the mechanism that can be applied to the suppression of the isolation grid frequency oscillation are analyzed. The working control strategy of the electronic load is introduced and the effects of different parameters are studied by the real time digital simulation system (RTDS). The results show that the electronic load device can participate in primary frequency control by means of the load dynamic control, which provides a new control idea for the suppression of frequency oscillation in the isolated network.