The invention provides a positioning mechanism for a folded-type motor home side coaming, and belongs to the technical field of motor home side coamings. The positioning mechanism for the folded-type motor home side coaming comprises a pedestal, a movable base, supports, two actuators and the side coaming. The cross section of the pedestal is arranged to be in a U shape, and the inner walls of the two sides of the pedestal are both provided with sliding rails. The movable base is arranged between the sliding rails and the bottom of the pedestal. The actuators are installed through the corresponding supports and act on the side coaming. According to the positioning mechanism, a motor and a crank structure are adopted to position the side coaming, positioning is made more accurate, and efficiency is made higher; the whole moving process is completed in the pedestal, the restriction that the surface of a floor is rugged is lowered, and adaptability is improved; the actuators are arranged and can only rotate by half a circle and then stop automatically every time of moving, and the side coaming can be stretched in place at a time; and a sensor is further arranged to collect positional information of the side coaming, a PLC is used for controlling, the overall stretching process is made more intelligent, and control is more convenient.