The manufacturing technology of large diameter thick wall seamless steel pipe belongs to the production method of large diameter thick wall seamless steel pipe. The production method is that the steel bar refined by electric furnace is refined by ladle and carried out under the protection of argon gas. After casting, the ingot is annealed and shaved at the bottom of the riser. After heating, the steel ingot is punched by a vertical hydraulic press, and then pulled by a horizontal hydraulic press. After stretching, reheating, stretching, heating to about 900 C, spraying water mist, quenching and tempering, grinding process of inside and outside crucibles, inside and outside round grinding process, non-destructive, shape detection and other products. By adopting the method of the invention, large-diameter thick-walled seamless steel pipes with an outer diameter of 325-1066.8 mm, a wall thickness of 25-162 mm and a length of less than 8500 mm can be produced. Seamless steel tube meets the national standard and can be used as power plant and high pressure boiler. Thick-walled seamless steel pipe, pressure vessel, cylinder, chemical steel pipe, centrifugal casting pipe die, etc.