Engine torque fluctuation is a great threat to vehicle comfort and durability. Former researches tried to solve this problem by introducing active damping system, which means the motor is controlled to produce torque ripple with just the opposite phase to that of the engine. By this means, the torque fluctuation produced by the motor and the engine can be reduced. In this paper, a new method is raised. An attempt is proposed by changing the traditional structure of the motor, making it produce ripple torque by itself instead of controlling the motor. In this way a special used ISG (Integrated Starter Generator) motor for HEV (Hybrid Electrical Vehicles) is made to achieve active damping. In order to study the possibility, a simulation, which focus on the motor instead of the whole system, is developed and series-parallel configuration is used in this simulation. As for the motor that used in this paper, four kinds of motors have been investigated and compared. Among which, SRM (Switched Reluctance Motor) has larger torque ripple, while PMSM (permanent magnet synchronous motor) has relatively high efficiency and is widely used. Hence, these two kinds of motors are simulated. And results show that simply reducing the number of magnetic poles is hard to match the engine’s torque ripple due to its higher frequency of fluctuation. But we can’t deny the possibility of other ways and more investigations and researches need to be done.