The utility model discloses a wire rope-assisted support leg laying/retracting device, and aims to provide a support leg device which is laid or retracted in a way of rotating 90 degrees longitudinally and sideways with the aid of a wire rope and is positioned on the lateral surface of a carriage after retraction to avoid the interference with the body of a semi-trailer during turning. Each support leg laying/retracting mechanism of the device comprises a rotating arm, an laying/retraction driving mechanism, a base plate and a traction wire rope, wherein the rotating arm is rotatably connected to the lateral surface of a vehicle body through a rotating shaft; the laying/retraction driving mechanism is fixedly connected with the rotating arm; one end of the traction wire rope is connected with a wire rope suspension hole on the lateral surface of the vehicle body, and the other end of the traction wire rope is connected with a hanger that is arranged on the telescopic rod of the laying/retraction driving mechanism; a spherical head is arranged at the end of the telescopic rod; the base plate is arranged at a supporting point; and a spherical head holder is arranged on the base plate in the position corresponding to the spherical head. The support leg device adopts the wire rope for traction to lay or retract the support leg in a way of rotating 90 degrees longitudinally and sideways, and enables the support leg to be retracted on the lateral surface of the carriage, so as to avoid the interference between the support leg and the tractor during turning.