The utility model discloses a pulley with a function of preventing a steel wire rope from being detached from a groove. The pulley comprises a pulley shell and the steel wire rope groove. Left and right arc-shaped holes which are not communicated with each other are formed in the pulley shell, are positioned on the outside of the steel wire rope groove and are arranged on the upper portion of the steel wire rope groove, the radian of each arc-shaped hole is identical to the radian of the steel wire rope groove, cylinders which are in slide fit with the arc-shaped holes are arranged at the outer ends of the arc-shaped holes, a hexahedron is arranged at one end of each cylinder and extends out of the corresponding arc-shaped hole of the pulley shell, threads which are matched with a nut are arranged at the other end of each cylinder, two springs are respectively arranged in the two arc-shaped holes, and two ends of each spring are respectively connected with the corresponding cylinder and the inner end of the corresponding arc-shaped hole. The pulley has the obvious advantage that the steel wire rope can be prevented from being detached from the groove.