The back electromotive force harmonics of a five-phase permanent magnet synchronous motor (FPPMSM) will significantly reduce the decoupling performance of a-dual-FPPMSM series drive system powered by a single inverter. Meanwhile, the traditional control strategy for the dual-FPPMSM series drive system based on an accurate motor model is too sensitive to changes in motor parameters. To solve these problems, the deadbeat control of decoupling between torque and flux is constructed at first, with flux amplitude and torque angle as the intermediate variables. Then, the speed ring active disturbance rejection control is established to generate the preset motor fundamental wave torque, based on which the torque ring active disturbance rejection control is constructed to generate the torque angle increment. Experimental results show that the proposed control strategy is insensitive to changes in motor parameters, and the decoupling performance between two motors is better.