The invention relates to a device for applying alternating tension to a high-voltage wire. The device for applying the alternating tension comprises a base, a power part, a transmission part and a driving part; the power part comprises a motor fixed on the base; the driving part comprises a tension-resistant wire clamp fixing mechanism used for being connected with a tension-resistant wire clamp of the high-voltage wire; the tension-resistant wire clamp fixing mechanism is in sliding connection with the base through a directional sliding assembly, and can slide on the base in the axial direction of the high-voltage wire; the transmission part adopts an eccentric wheel and a connecting rod for transmission, and comprises the eccentric wheel connected with the output end of the motor, and the transmission connecting rod; and one end of the transmission connecting rod is hinged to the eccentric wheel, and the other end of the transmission connecting rod is hinged to the tension-resistantwire clamp fixing mechanism. According to the device, the alternating tension can be applied to the high-voltage wire by utilizing a driving mechanism; the influence of the alternating tension on thehigh-voltage wire in the axial direction is simulated; and reference data is provided for safety evaluation of a power transmission line in a strong wind area.