The invention discloses a transformer substation indoor screen cabinet detection device based on an inspection robot and a detection method of the transformer substation indoor screen cabinet detection device. The inspection robot moves frontwards along a guide rail; when the inspection robot enters the side of a screen cabinet to be inspected, a telescoping mechanism stretches; a position detection device is used for identifying a position label; when the position detection device detects the position label, the position label is identified and the inspection robot is used for detecting the screen cabinet; after the detection is finished, the next step is carried out; when the position label is not detected, the next step is directly carried out; the robot continually moves along the guide rail and the next position label is found to inspect; after the robot moves along the guide rail, the inspection robot inspects in the opposite direction. The transformer substation indoor screen cabinet detection device has good safety protection measures; the robot does not interfere with the screen cabinet in a door opening and closing process and equipment is not damaged. Not only can the effective inspection be carried out on the single row of screen cabinet, but also the effective inspection can be carried out on a plurality of rows of the screen cabinets; the guide rail can be randomly spliced into various shapes according to the arrangement condition of the screen cabinet and the inspection is flexible; the all-directional inspection on the screen cabinet can be realized.