The invention discloses a method for suppressing sub-synchronous oscillation of a wind power transmission system through series compensation by a superconducting magnetic energy storage and a controlsystem for suppressing sub-synchronous oscillation of a wind power transmission system through series compensation by a superconducting magnetic energy storage. The method comprises the steps of: thestep A, monitoring a bus power condition at the exit of a wind power plant in real time; the step B, if the control system determines the generation of sub-synchronous oscillation, starting an activeouter ring additional damping controller of a superconducting magnetic energy storage controller; the step C, observing the change state of the sub-synchronous oscillation, and if the convergence rateof the sub-synchronous oscillation does not reach a preset standard, starting a reactive outer ring additional damping controller of the superconducting magnetic energy storage controller; and the step D, when a sub-synchronous component of the power of the wind power plant in the system is smaller than an assigned value, quitting the outer ring additional damping controllers of the superconducting magnetic energy storage controller. Based on the sub-synchronous oscillation suppression method and the control system, on the basic function of the superconducting magnetic energy storage, the flexible and changeable operation conditions of the wind power plant can be adapted so as to effectively suppress the sub-synchronous oscillation of the wind power plant.