The present invention relates to a method and device for suppressing influence on a wind turbine generator caused by a negative sequence due to an electrified railway. The method includes the following steps that: a simulation model is constructed according to an actual traction power supply system structure, and the cause of the negative sequence of traction power supply is analyzed, the mathematic model of a doubly-fed wind turbine under an unbalanced condition is established according to the cause of the negative sequence of the traction power supply; the mathematical analysis model of the influence on the operating characteristics of the doubly-fed wind turbine caused by negative-sequence current due to electrified railway traction load is built through using the mathematic model of the doubly-fed wind turbine under the unbalanced condition; and a control optimization strategy is obtained through using the mathematical analysis model, according to the control optimization strategy, the traditional double-closed-loop vector control mode of a doubly-fed wind turbine is changed, and a proportional resonance controller is adopted to suppress second harmonic frequency components caused by the negative sequence.