During the past two decades, the doubly fed induction generator (DFIG) based wind farm has been under rapid growth, and the increasing wind power penetration has been seen. Practically, these wind farms are connected to the three-phase ac grid through long transmission cable which can be modeled as several II units. The impedance of this cable cannot he neglected and requires careful investigation due to its long distance. As a result, the impedance interaction between the DFIG-based wind farm and the long cable is inevitable, and may produce high-frequency resonance (HFR) in the wind farm. This paper discusses the HFR of the large-scale DFIG-based wind farm connected to the long cable. Several influencing factors, including 1) the length of the cable, 2) the output active power, and 3) the rotor speed, are investigated. The transformer leakage inductances in the transmission system are taken into consideration when investigating the HFR. Simulation validations using MATLAB/Simulink have been conducted to verify the theoretical analysis.