A natural convection roof device includes a first roof drainage panel, a first extended roof drainage panel, a second roof drainage panel, an inner barrier and an inner roof containing an inner ventilation opening disposed obliquely to the first roof drainage panel. The top end of the first roof drainage panel includes the first extended roof drainage panel, and the top end of the first extended roof drainage panel is assembled with the second roof drainage panel and the inner barrier. The bottom ends of the second roof drainage panel and the inner barrier are installed on the inner roof. The lower side of the inner barrier is center ventilation openings. Above the second roof drainage panel is ventilation holes, and below the second roof drainage panel is drain holes. The level of the ventilation holes is higher than that of the inner ventilation opening.