Disclosed is a buffer assembly of a vacuum molding and cutting machine, and the buffer assembly includes a lower mold base, at least four hydraulic elements and a movable plate. The lower mold base has at least four installing holes for installing the hydraulic elements respectively, and each hydraulic element includes a piston plunger for propping the movable plate to a predetermined distance. When the cutting thickness is 0.1 mm-0.5 mm of a sheet, the impact force can be absorbed effectively to maintain the parallelism for the cutting, so as to improve the cutting quality and extend the service life of a die cutting tool.