The invention discloses a power supply transfer junction box, which comprises a box body with a detachable upper cover. Multiple groups of plug interfaces are formed in the upper cover; the inner bottom surface of the box body is provided with multiple rectangular slots; each of two inner sides of the rectangular slot is provided with at least one copper sheet slot for placing a copper sheet; the copper sheet slot is internally provided with a plug interface passing through the bottom surface of the box body; a slide switch is arranged in the middle of the copper sheet slots at two sides; the slide switch moves vertically to contact the copper sheet, and thus, on or off of circuits at two sides is achieved; and a rail for enabling the slide switch to slide is arranged on the box body. According to the power supply transfer junction box provided in the invention, line transfer from normal mounting to unconventional mounting can be quickly realized, cutting of a motor lead can be effectively avoided, various problems caused by cutting of the lead are not generated, the power supply line reliability is improved; and besides, when the power supply transfer junction box is applied, an unconventional test can be carried out in any safety distance, occurrence of personal accidents is avoided, operation by a tester is facilitated, and system test requirements are met.