Disclosed is a banknote separation device and a radial lash adjusting method therefor. The banknote separation device comprises a banknote separation wheel set (20) and a reverse wheel set (30) in cooperation with the banknote separation wheel set (20), wherein the reverse wheel set (30) comprises a reverse wheel component, a reverse wheel set rotation shaft (32), a first fixing frame (33) and a second fixing frame (34), wherein two ends of the reverse wheel set rotation shaft (32) are fixed on two mounting side plates in self-service banking equipment respectively, the first fixing frame (33) and the second fixing frame (34) are respectively fixedly connected at two ends of reverse wheel component The first fixing frame (33) is provided with a first lash adjusting threaded hole (331) and a first lash adjusting screw (301) cooperating therewith, the second fixing frame is provided with a second lash adjusting threaded hole (341) and a second lash adjusting screw (302) cooperating therewith, and radial clearan
