The present invention discloses a sectional fan frame structure composed of two units or two units and a circular plate frame. The units can be made in different shapes as needed, and the units come with fasteners. The circular plate frame is formed by enclosing a plate, and the fasteners are installed at the positions of connecting the circular plate frame and the units. Therefore, a fan frame can be assembled by the latch of fasteners between the units, or the unit and the circular plate frame, so as to achieve the effects of simplifying the development of a mold, providing an easy demold after an injection molding, assembling a fan frame with a different height by changing the width of the circular plate frame, and saving the cost of the mold.