The invention discloses a setting structure for a guard board of an escalator or moving pavement machine room. According to the invention, the guard board is driven to move forward and backward through a connecting part, so that a size of the front part and the rear part of a maintenance space can be adjusted, so as to ensure an escalator or a moving pavement with a shortened truss to have enough maintenance space; for the escalator or moving pavement with a standard truss, the maintenance space maximized can be realized, so as to be convenient for maintenance; when the guard board moves forward and backward to a proper place, the connecting part only needs to be locked on a fixed seat through a first locking mechanism; the guard board can move left and right, so that one kind of guard board can be applicable to multiple escalators or moving pavements with different widths; and when the guard board or the connecting part moves left and right, the positioning of the guard board can be realized by using a second locking mechanism to lock the guard board on the connecting part.