Abstract: Due to the complexity of detailed modeling,the stability analysis of grid-connected wind farms usually adopts the single-machine equivalent model（SEM）. However,the applicability of SEM for small disturbance stability analysis of grid-connected wind farm systems is still uncertain. Therefore,this paper proposes a comprehensive evaluation method from both numerical and trend aspects to compare the accuracy of the oscillation pattern characteristics before and after the equipartition,and analytically illustrates the adequacy of SEM.First,the grid-connected wind farms are modeled with two common single-machine equivalence methods for singlemachine equivalence;second, the accuracy of the singlemachine-equivalent model and the full-order model subsynchronous oscillation pattern of the wind farm under the conditions of permanent magnet synchronous generator（PMSG）parameters and the variation of the wind farm structure is investigated. The results show that the single-machine equivalence reduces the accuracy of the sub-synchronous oscillation mode, and the applicable scenarios of different equivalence methods are different.