The invention discloses a spiral chute installation structure and an installation method. The spiral chute installation structure comprises a lower circular hollow short pipe base fixedly arranged on a ship body, and an upper circular hollow short pipe base fixedly connected to the lower end surface of a spiral chute upper cover plate; the inner diameters of the upper and lower circular hollow short pipe bases are larger than the outer diameter of a spiral chute center round pipe by 3-4 mm; during installing, firstly, the lower end of the spiral chute center round pipe is inserted in the lower circular hollow short pipe base; then, the spiral chute upper cover plate is put between I beams of a ship body structure, and the upper circular hollow short pipe base is downwards pressed while coating the upper end of the spiral chute center round pipe until the spiral chute upper cover plate is contacted with the lower edges of the I beams; and the spiral chute upper cover plate is connected with the lower edges of the I beams through bolts. The spiral chute installation structure is mainly suitable for building work of an offshore mining and beneficiation integrated ship, an offshore beneficiation platform or a beneficiation ship.