The invention discloses a visualization experiment device and method for cutting stress waves in a vertical milling machine. The device comprise an optical system, a clamping body, a machining workpiece and the vertical milling machine; the optical system comprises a reflector, a light source which is horizontally arranged, ground glass, a polarizer, an analyzer and a high-speed camera, wherein the ground glass, the polarizer, the analyzer and the high-speed camera are sequentially and coaxially arranged from bottom to top in the vertical direction; a main shaft of the vertical milling machineis perpendicular to the machining workpiece and is fed along the plane direction of the machining workpiece; the machining workpiece is fixed at the upper end of the clamping body, and the ground glass and the polarizer are arranged on the clamping body; and the reflector is arranged below the ground glass, and is arranged on a horizontal light path of the light source to form a turning light path, and the turning light path sequentially irradiates the ground glass, the polarizer and the machining workpiece, and then is collected by the high-speed camera through the analyzer. According to thedevice and the method, the reflector with the adjustable angle is adopted, so that the optical path system does not need to be sequentially arranged in the direction of the main shaft of the verticalmilling machine, and the internal stress wave propagation of the material can be observed under a high-speed cutting state.