Aiming at the difficulty of mechanized construction of large-diameter shafts in the upper soft and lower hard strata, a mechanized construction method for large-diameter shafts in the upper soft and lower hard strata is proposed with the background of the 2# working well in section 2 of Shenzhen Daping Interval. This method adopts a CJM sinkhole boring machine for construction in the soft rock section, converts the working method in the soft and hard junction section, and adopts a mechanical rock-breaking method for construction in the hard rock section. In this paper, the construction process and key construction technology of the aforementioned mechanized construction method of the large-diameter shaft are studied in detail, and the prefabricated assembled shaft structure design theory is studied, and a large-diameter shaft assembled shaft structure design scheme is proposed, and finally, the internal force of the shaft structure and the influence of the surrounding strata in the process of mechanized construction of the large-diameter shaft are studied, and the results show that this method has a small influence on the surrounding strata of the shaft, and the most unfavorable location of the shaft structure force is one of the most unfavorable locations of the shaft structure. The most unfavorable position of the shaft structure force is located near the position above the soil-rock interface.