To the sub-synchronous oscillation in the doubly fed induction generator (DFIG) system with static var generator (SVG), a feedback linearization control method for the rotorside converter (RSC) is proposed, and its oscillation mitigation effect under small/large disturbances is analyzed and verified. Firstly, a 22-order time-domain model of a DFIG system with SVG is established. Secondly, combined with the principle of feedback linearization, the corresponding control method is designed for RSC inner loop control. Thirdly, the effects of PI control and feedback linearization control on the system stability are compared when different parameters change under small disturbance. Finally, considering the effect of the limiting link, the stability of the system RSC inner loop using PI control and feedback linearization control under large disturbance is analyzed. The results show that the feedback linearization control can effectively increase the attraction domain of the equilibrium point and improve the system stability.