The invention discloses an electromechanical equipment repairing mechanism for a mobile transformer substation. The electromechanical equipment repairing mechanism comprises a spliced base, a movable frame and a support frame, wherein the spliced base is a strip-shaped plate body formed by splicing a plurality of splice plates; a top surface of the spliced base is provided with a groove; a bottom iron plate is embedded into a bottom surface of the groove; the bottom iron plate is provided with a plurality of bumps; the movable frame is a regular quadrangular frustum pyramid-shaped frame body formed by integrally molding a bottom panel, four support columns and a top panel from bottom to top; the bottom panel is arranged in a sliding way along the length direction of the spliced base; the support frame comprises a vertical rod and a horizontal rod of which end parts are hinged together; a chock plug which is matched with the groove is fixedly arranged at a bottom end of the vertical rod; a top surface of the top panel is provided with a support; the support is provided with a through hole; and one end of the horizontal rod horizontally passes through the through hole. A length-adjustable spliced substrate on which the movable frame walks is formed by splicing the plurality of splice plates, and is suitable for narrow spaces of different transformer substations, so that a stable base is provided for the movable frame, and the movable frame can slide along a slide way to enlarge an operating platform for a worker to repair electromechanical equipment.