This paper focuses on the dynamics characteristic difference on the two kinds of broading machine, the workpiece moving and the cutting-tool moving. There is 0.002mm thickness of oil-film clearance between the mobile and immobile components of the broading machine. Hydraulic pressure derived from the driving oil cylinder drives the workpiece or cutting-tool moving, while the material on the workpiece is cutting. Cutting-tool of the machine is an external expand cutter with the groove for breaking the cutting waste, the manufacturing phase is a pulse impact cutting exciting applying on the broading machine correspondingly. On manufacturing, natural characteristic of the broading machine is approximately the pulse impulsion frequency of the machine;response amplitude of the lather is increasing manifesting. The study is focused on the dynamics characteristic of two kinds of broading machine, the difference is workpiece or cutter moving, to predict the manufacturing performance.