A patrol and examine dolly that is used for suspension type mono -rail transport system box track roof beam, the utility model relates to a traffic technique and computer technology. The utility model discloses an automobile body and visual detection part, the visual detection part is installed in the automobile body, the automobile body includes chassis, car shell, drive unit and traffic control unit, and drive unit and traffic control unit connection are provided with the seat in the automobile body, still is provided with the radio communication unit in the automobile body, drive unit includes the drive wheel, follows driving wheel, leading wheel, the leading wheel sets up in the left and right sides of automobile body, and the leading wheel of one side passes through spring and car connection at least. The utility model discloses the utilization equipment of patrolling and examining carries the visual system and replaces the manual work to patrol and examine, has not only solved because the box inner space of box track roof beam is narrow and small, light is dim, and the bottom opening is narrow for the great problem of the degree of difficulty is patrolled and examined in the manual work, can also show to improve to patrol and examine efficiency and reliability.