The invention discloses a deepwater platform construction device and a construction method based on high flow speed and large waves. The deepwater platform construction device comprises large-diameter steel pipe piles and a platform upper structural system, wherein transverse partitions are arranged in the large-diameter steel pipe piles, and the side walls of the transverse partitions are fixed to the inner walls of the large-diameter steel pipe piles; the lower parts of support leg piles of the platform upper structural system extend into the large-diameter steel pipe piles until the lower parts of the support leg piles are abutted against the transverse partitions, the outside diameter of each support leg pile is less than the inside diameter of each large-diameter steel pipe pile, and the positions, which extend into the large-diameter steel pipe piles, of the support leg piles are connected with the inner walls of the large-diameter steel pipe piles by pouring concrete. By adopting the large-diameter steel pipe piles, large water flow force and wave force can be resisted; the concrete is poured for connection, so that the overwater welding operation is reduced, the welding quality is guaranteed, the construction risk is reduced, and the deepwater platform construction device can adapt to the condition different from the actual situation.