The invention relates to a swing preventing mechanism for a steel wire rope of an elevator. The steel wire rope of the elevator vertically operates in an opening of an anti-swing structure; a first guide device is arranged on a lift car and is located at the same side with the opened end of the anti-swing structure, and the closed end of the anti-swing structure is connected with a sliding device after passing through a second guide device; and a threaded rod is fixed at the same side of elevator guide rails through first fixing support frames, two swing arms are fixed on the threaded rod through a second fixing support frame and can vertically swing around a shaft fixed on the second fixing support frame, the other ends of the two swing arms are connected with a second guide device, a regulating device is arranged between the two swing arms, a two-stage damping spring is arranged on a position of a central connecting line of the regulating device and the sliding device, one end of each of two inclined tension springs is located at the upper and lower end of the second guide device, and the other ends of the two inclined tension springs are relatively arranged at two ends of the threaded rod. The swing preventing mechanism is novel in structure, reliable in performance, convenient to mount and debug and capable of effectively solving the swing problem of the steel wire rope of the elevator and particularly steel wire ropes of marine elevators and elevators with large lifting heights.