The large-scale access of wind power causes a significant reduction in the inertia of the power system, seriously threatening the security and stability of the system frequency. Inertia control methods based on the optimized PLLs provide a solution to the low inertia problem of doubly-fed inductance generator (DFIG)-based wind turbines (WTs), but they still suffer from poor dynamic performance and obvious phase-locked error in steady state. For this reason, a novel inertia control method for DFIG-based WTs is proposed in this paper to support the system frequency with better performance in all aspects. Firstly, an equivalent inertia model is deduced considering the dynamic of control and the reason why modifying PLL can realize inertia response of WT is analyzed. Then, the existing inertia control methods based on optimized PLL is introduced and a novel inertia control method with phase-locked error feed-forward in PLL (pefPLL) is proposed. After that, the inertia characteristics, dynamic performance, and steady state performance of pefPLL and other PLLs are compared. Finally, the superiority of the novel inertia control method with pefPLL is verified by simulations.