The invention discloses a supporting device for reducing vibration of a large-size oil pipe in thread machining, and a use method. The supporting device comprises an impact bearing mechanism, wherein the impact bearing mechanism comprises a supporting gasket (1), and a positioning block (2) is fixedly connected to the bottom of the supporting gasket (1); the positioning lock (2) is coated with a gasket (3), and the gasket (3) is coated with a limiting block (4); the limiting block (4) is installed inside a supporting frame (5); and the upper surface of the supporting gasket (1) is semi-arc. The supporting device disclosed by the invention has the beneficial effects that the vibration of the oil pipe in the thread machining is reduced; and processing accuracy and a service life of a cutter are increased.