The invention relates to a screw fastening tool, in particular to a horizontal screw charged fastening tool of a transformer substation device, wherein the problem that horizontal screw charged fastening tools are in shortage at present is solved. The fastening tool is composed of an insulating operation rod and an operation head. The operation head comprises a hollow U-shaped operation head body. A moving rod with a rack on the lower end face is arranged at one end of a vertical column on one side of the U-shaped operation head body. One end of the moving rod is connected with a short sleeve. A gear meshed with the rack on the lower end face of the moving rod is supported in a cavity of the U-shaped operation head body. A driven shaft is supported by one end of a vertical column on the other side of the U-shaped operation head body. One end of the driven shaft is connected with a long sleeve. A supporting plate is arranged on the other side of the vertical column on the other side of the U-shaped operation head body. A driving shaft is supported by the supporting plate. The other end of the driving shaft is connected with one end of the insulating operation rod in an inserted mode when used. The horizontal screw charged fastening tool is reasonable, novel and unique in structural design and is an ideal horizontal screw charged fastening tool of the transformer substation device.