Abstract: The small-disturbance oscillation stability of the direct-drive permanent magnetic synchronous generators (PMSG) is closely related to the dynamic characteristics of the grid-side converter (GSC). Most of the existing researches on the small-disturbance stability of grid-connected PMSG wind farms in the AC current time scale ignore the coupling effect between the power control outer loop and the current control inner loop directly, and there are few researches on discussing the influence of the outer loop on the dynamic interaction process between the inner loop and the phase-locked loop (PLL). In order to fulfill the research gaps above, this paper establishes the reduced-order equivalent model of a large-scale PMSG wind farm, and explores the influence of the power control outer loop on the small-disturbance oscillation stability under the AC current time scale of the wind farm based on the methods of model analysis, modes analysis, and time-domain simulation. The research results and conclusions indicate that the power control outer loop and the current control inner loop may become coupled when the parameters are tuned improperly, and ignoring the interaction between them directly may cause errors during the stability analysis under the AC current scale. The interactive path between the current control inner loop and the PLL is established through the power control outer loop, and change of the parameters of the outer loop will have a certain impact on the dynamic interaction between inner loop and PLL.