The invention discloses a manufacturing method of a large-diameter steel pipe pile for a piece of offshore wind power equipment. The manufacturing method includes the following steps: step 1, preparing a steel plate having a thickness of 45 mm to 70 mm, a width of 3 to 4 meters and a length determined by a diameter of a required steel pipe pile; step 2, bending the steel plate into a cylinder pipe by a plate bending machine; step 3, welding a longitudinal seam of the cylinder pipe; step 4, rounding the welded cylinder pipe; step 5, lifting three sections of the cylinder pipe onto an assembling roller frame by a crane and adapting a internal-external girth welding on seams between every adjacent two sections of the cylinder pipe. The manufacturing method of a large-diameter steel pipe pile for a piece of offshore wind power equipment provided by the invention overcomes difficulties in manufacturing and processing supper large-diameter and extra heavy steel pipe piles, providing a strong support for introducing single pipe pile construction technology to offshore wind power industry and a significant reduction in engineering cost.