Machining method and machining tool for lifting vertical lathe to machine small-diameter cylinder

The invention discloses a machining method and machining tool for a vertical lathe to machine a small-diameter cylinder. The machining method comprises the steps that according to the machining tool for the vertical lathe, the minimum rotating diameter size of a vertical tool rest of the machining tool is calculated, the total length C of a turning tool bar of the vertical lathe is calculated, the turning tool bar and the vertical tool rest of the vertical lathe are fixed through a bolt, a turning tool clamping part is arranged on the turning tool bar, a turning tool blade is clamped at the turning tool clamping part, the length, exceeding the vertical tool rest, of the tool nose of the turning tool blade is D, the length of the turning tool blade clamping part is E, D must meet the condition that D is larger than or equal to E/2, the shortest distance after the vertical tool rest and the turning tool bar are clamped is calculated as the sum of L and E, and when the vertical lathe machines the inner circle of