The invention relates to the field of warning devices, and more particularly relates to an overhead line warning device. The overhead line warning device comprises a hanging mechanism and a warning mechanism. The hanging mechanism and the warning mechanism are connected. The warning mechanism is composed of a light-emitting device and a light reflecting film. The light reflecting film can reflect the sunlight in the daytime to realize the warning effect. The light-emitting device is provided with solar panels, a cell, a circuit board and LED lamps and can perform charging through solar energy in the daytime and automatically connect the circuit between the cell and the lamps through the circuit board chip at night to light up the LED lamps so as to achieve the warning effect. The overhead line warning device is simple in structure and can realize the all-day warning effect, and the device can be installed and detached by using the common insulating rod so that use is convenient and economical.