The invention discloses a protection device for preventing windage yaw flashover of a power transmission line. The device comprises a wire, a fitting connected with the wire, a power transmission line insulator, a fitting protection device and two wire protection devices located on the two sides of the fitting. The wire protection devices are arranged outside the wire and connected with the fitting protection device, and the fitting protection device is installed outside the fitting and connected with the power transmission line insulator. Specific to air breakdown and discharge, the most direct reason for windage yaw flashover, generated due to the fact that the insulating distance between the wire and a tower is not enough due to strong wind, the electric insulating strength between the wire and the tower is enhanced. By the adoption of the protection device, electric field distortion between the wire and an insulating sheath and between the fitting and an insulating sheath box is effectively eliminated, and it is avoided that partial field strength is too high and the effect of preventing windage yaw flashover is greatly reduced; water is effectively prevented from entering the insulating sheath and the insulating sheath box, the probability of corona of the wire and the fitting is reduced, and the problem of electrochemical corrosion and aging of the device is solved.