Abstract: To the problem of sub-synchronous oscillation(SSO) caused by the saturation of the limiter, the current researches mainly focus on the influence of the limiter on the grid-connected voltage sourced converter (VSC) system, while the theoretical analyses on the influence of the limiter on the DFIG-based SSO in power system are seldom reported. In this paper, focusing on the power system connected with double-fed induction generators (DFIG) and static var generators (SVG), combined with the influence of limiters on impedance, a impedance method considering the limits is proposed to approximate analysis the phenomenon of SSO engaged with limiters(SSO-L). This analysis reveals that the mechanism of SSO-L is related to the system impedance characteristic with limiters, different from the traditional characteristic. In detail, firstly, the DFIG-based wind power system with SVG and its limiters, as well as the phenomenon of SSO-L are introduced; Secondly, combined with the description function, the impedance model of the simplified DFIG-based wind power system with limiters is established; Thirdly, combined with the impedance model with limiters, the mechanism of the SSO-L is revealed, that is, when the SVG limiter is saturated, the impedance of the DFIG-based wind power system with limiters changes from a positive resistance to negative, resulting in the SSO-L. Finally, considering the cases retaining/removing the limiters, the influence of different limiter values and other control parameters on the impedance characteristics of the system with limiters and the characteristics of the SSO-L is analyzed.