The invention discloses a supporting structure for reinforcing landslide and a construction method of the supporting structure. The supporting structure comprises bottom-expanded anti-slide piles (1),a pile top crown beam (2) is fixedly arranged at the tops of the bottom-expanded anti-slide piles (1), the pile top crown beam (2) is fixedly connected with a plate wall (3) through steel bars, waterguiding pipes (5) are arranged inside the plate wall (3), and the plate wall (3) is locked and reinforced by prestressed anchor cables (4). Compared with an existing slope supporting structure, the combined supporting structure can adapt to a special slope body with the gentle lower part and the steep upper part, the horizontal and vertical bearing capacity of the bottom-expanded anti-slide pilesis given to full play, construction is convenient and fast, and the project cost is saved.