Abstract: In virtue of the elimination of the brushes and the slip rings, the brushless doubly-fed induction generator (BDFIG) is a potential alternative to the well-known DFIG in the wind power generation field due to its high reliability and low maintenance costs. However, the interaction and instability mechanism between the BDFIG-based system and the weak AC grid still remain unaddressed, resulting in some difficulties in its practical application and commercial promotion. In order to settle such problems, the input admittance model of the BDFIG system is established based on the small-signal impedance modeling method, which considers the influence of both the current loop and the phase-locked loop. Then the transmission paths of the grid voltage disturbance in the control system are explored. In particular, the impact mechanism of the operating points (the active and reactive currents) on the system stability under the weak grid condition is estimated in detail. Accordingly, the current references of the BDFIG system are derived. Meanwhile, the effecting pattern of the virtual inductive on the system stability is studied and the parameter tuning method of the virtual inductive control strategy is proposed to enhance the stability of the system. Finally, the simulations verify the correctness of the theoretical analysis and the effectiveness of the proposed control strategy.