The invention discloses an outdoor railway power supply box with a control unit, which comprises a power supply box body. A control branch box with a built-in control unit is arranged on the low-voltage side face of the power supply box body; and a heat insulation layer is arranged on the inner wall of the control branch box. Through adopting the technical scheme that the control branch box is additionally arranged on the low-voltage side face of the power supply box body 1, two box bodies are integrated into one, and the purpose of reducing the entire size is achieved; the heat insulation layer additionally arranged on the inner wall of the control branch box can play the role of heat insulation, and therefore the temperature inside the box body can be prevented from changing along with the ambient temperature, and stability and the service life of the box body are improved; and the outdoor railway power supply box with the control unit can be applied to the railway.