The invention provides a crankshaft eccentric circle machining tool and machining method. The crankshaft eccentric circle machining tool comprises a first cylinder (1) and a second cylinder (2) whichare arranged in the axial direction in sequence. The first cylinder (1) and the second cylinder (2) are eccentrically arranged. The eccentric distance of the first cylinder (1) and the second cylinder(2) is equal to that of a crankshaft eccentric circle. The second cylinder (2) is provided with a fixing part used for fixing a crankshaft (11). The crankshaft (11) and the second cylinder (2) are concentrically arranged. The crankshaft eccentric circle machining tool provided by the invention is high in machining efficiency and machining precision.