The invention provides a method and system for suppressing subsynchronous oscillation of a wind power system. The method comprises steps that a pre-designed local variable gain controller is connectedin series with a converter control input end; parameter values of the local variable gain controller are determined based on the topology structure of the wind power system and the access location ofthe local variable gain controller; the gain of the converter control input end is reduced based on the local variable gain controller to suppress subsynchronous oscillation of the system; and the local variable gain controller is designed according to the access location, the structure and the parameters. The method is advantaged in that easy realization and strong practicality are achieved, subsynchronous damping of the system can be effectively improved, subsynchronous oscillation is reduced, parameter design model dependence of a subsynchronous damping controller is avoided, and robust stability problems due to model errors and the like are avoided.