A bundle beam UV LED ultraviolet light sweeping method includes: activating electrical power to input into a PCB to light up a bundle beam UV LED ultraviolet light bead and driving a motor to cause a polygonal multiple-reflective-surface aluminum mirror to rotate, ultraviolet light from the UV LED being projected toward the reflective surface, and reflected by the reflective surface to change light direction for successive back-and-forth home-position-returning sweeping, the light converting from lines into sectorial shapes that are connected to form a large ultraviolet light operation region. The device includes a rotating device having a motor of which a spindle is mounted with a polygonal multiple-reflective-surface aluminum mirror; an UV LED bundle beam light source assembly having a bundle beam UV LED ultraviolet light bead fixed on a PCB; and a fixing base having a main body and a plurality of mounting braces.