The invention relates to a large-stroke tensioning device in a wheel machining process. The large-stroke tensioning device in the wheel machining process comprises a base (1), a servo motor (2), a mounting plate (3), a connecting plate (4), a shaft sleeve (5), an oil cylinder (6), a gland (7), bearings (8), a connecting shaft (9), a chassis (10), positioning pins (11), a flange plate (12), springs (13), sliding pedals (14), an expanding core (15), a protector (16) and the like. The large-stroke tensioning device can meet requirements of clamping and positioning of a wheel, and meanwhile has the characteristics of simple structure, convenience in manufacturing, stable performance and capability of meeting machining requirements on precision.