The invention belongs to the technical field of power system subsynchronous oscillation suppression method, and particularly relates to a subsynchronous oscillation suppression system and a subsynchronous oscillation suppression method based on synchronous coordinate torque vector control. The subsynchronous oscillation suppression system method specifically comprises the steps of: taking a generator shafting torsional vibration rotating speed deviation signal as input of a controller, converting the rotating speed deviation signal into two frequency components at a stator side corresponding to the same by adopting conversion from a synchronous coordinate system to a stationary coordinate system, and taking the two frequency components as an instruction value of compensating current; controlling a phase relation between two frequency currents through parameter optimization, so that an amplitude value of total additional electromagnetic torque formed by the two frequency currents reaches the maximum; and controlling an included angle between the electromagnetic torque and the rotating speed deviation signal through parameter optimization, so that the total additional electromagnetic torque achieves the optimal damping effect.