In order to improve the output power and conversion efficiency of the High Power Microwave(HPM) device, a novel resonator Split Cavity Oscillator(SCO) is proposed, which is driven by the Magnetically Insulated Linear Oscillator(MILO) magnetically insulated current, in place of the collecting electrode, by analyzing the characteristics of the MILO and SCO, to form a dual-band hybrid HPM device with higher output performance. Simulation results of the whole electromagnetic particle simulation software show that the L-band MILO-SCO hybrid HPM device can work at 1.54 GHz and 0.74 GHz dual-band with the conversion efficiency more than 20%. This work can provide reference for improving HPM devices performance.