The invention discloses a cleaning device for glass windows. The cleaning device comprises a mounting plate body (9), a cleaning scraper (90) which is arranged on the front end face of the mounting plate body (9) and a frame body (8) which is fixedly connected to a holding rod 3, wherein two elastic fixing plates (91), which are vertically symmetrical, are arranged at the back side of the mounting plate body (9); two conical inserting holes and a bent convex platform part (911), which is arranged between the two conical inserting holes, are arranged on each elastic fixing plate (91); a mounting frame body (6) is arranged at the front side of the frame body (8); and two conical bumps (69), which extend towards an inner cavity (60) of the mounting frame body (6) and are longitudinally arranged, are arranged on each of an upper sidewall (61) and a lower sidewall (62) of the mounting frame body (6).