Reducing pile for jacket and jacket leveling method

The invention relates to a variable-diameter pile for a jacket and a jacket leveling method, the variable-diameter pile for the jacket comprises an upper pile section, a variable-diameter pile section and a lower pile section, and the upper pile section is columnar; the lower pile section is columnar, and the size of the cross section of the lower pile section is larger than that of the cross section of the upper pile section; the variable-diameter pile section is arranged between the upper pile section and the lower pile section; wherein the upper pile section, the lower pile section and the reducing pile section are an integrated pile, and the interior of the reducing pile is hollow; when the variable-diameter pile is installed, a small-pile-diameter pile hoisting device and a small-pile-diameter leveling device can be applied, hoisting of the variable-diameter pile and leveling of a jacket are achieved, the purchase cost of the pile hoisting device and the leveling device is reduced, and the development co