The invention discloses a fixing device used for power transmission line monitoring equipment. The fixing device is characterized in that the fixing device comprises an angle steel locking structure,a T-shaped support, a solar cell fixing support and an equipment mounting support; the angle steel locking structure is fixedly connected with angle steel of an overhead iron tower; the T-shaped support is mounted in an inverted-T shape, one transverse end of the T-shaped support is fixedly connected with the angle steel locking structure, and the equipment mounting support is fixedly arranged atthe other transverse end of the T-shaped support; and the solar cell fixing support is fixedly arranged at the upper end of the T-shaped support. The fixing device is suitable for being fixed to anglesteel of various specifications and can meet mounting requirements of various power transmission line detection devices.