Abstract: The sub-synchronous oscillation (SSO) of direct drive permanent magnet synchronous generator (D-PMSG)-based wind farm incorporated into weak AC grid threatens the safe operation of power system. The analysis of sub-synchronous component path can reveal the sub-synchronous interaction characteristics within the system and analyze the damping characteristics of each path separately. At present, there is no literature to carry out relevant researches. To resolve the above problems, this paper first established the closed-loop transfer function block diagram of the D-PMSG-based wind farm incorporated into the weak AC grid system, and analyzed the D-PMSG DC capacitor-dominated oscillation mode using the damping torque method. Then, based on the transfer function block diagram, two sub-synchronous component paths were obtained by analyzing the sub-synchronous component path inside the D-PMSG-based wind farm, and the sub-synchronous component path between the D-PMSG-based wind farm and the weak AC power grid. Finally, the influence of the parameters of the grid-side controller (GSC) of D-PMSG on the damping characteristics of the two paths was analyzed by using path damping analysis and time domain simulation. The results show that when the integral coefficient of the GSC DC voltage outer loop increases, the damping of the two sub-synchronous component paths decreases; the reduction of the proportional coefficient of the DC voltage outer loop and the proportional and integral coefficients of the current inner loop could reduce the damping of the sub-synchronous component path in the D-PMSG-based wind farm. The research results have certain guiding significance for the design of the damping controller.