A spherical anti-bird device for a power transmission overhead line is in a steamed bun cover shape, a middle baffle (4) is arranged at the middle position of the spherical anti-bird device for the power transmission overhead line, two end face baffles (5) are arranged at the left end and the right end of the spherical anti-bird device for the power transmission overhead line, and the lower edges of the front faces and the back faces of the left end face baffle (5) and the right end face baffle (5) are respectively welded to a fixing device. A telescopic baffle (3) is mounted at one end of the middle baffle (4) of the middle part of the spherical anti-bird device for the power transmission overhead line. The fixing devices are of a horizontal n shape, the openings of the fixing devices face outwards, holes are formed in the lower bottom faces of the fixing devices, and plug pins (1) for fixing and plug pins (2) for fixing are inserted in the holes. According to the spherical anti-bird device for the power transmission overhead line, the service life is prolonged, the replacement period of the device is shortened, and economic benefits are increased; the structure is stable, the size is small, operation is simple, mounting is convenient, the difficulty for mounting of the spherical anti-bird device for the power transmission overhead line on a pole or a tower can be lowered, and working efficiency can be improved; the spherical anti-bird device for the power transmission overhead line is suitable for cross arms of any specifications. After the spherical anti-bird device for the power transmission overhead line is mounted, birds cannot build nests on the spherical anti-bird device, the problem that the birds have tolerance to bird repelling devices is solved, and operation and maintenance cost is lowered.