The invention discloses a method for laying out a leading rope by a helicopter. The method comprises the following steps of setting a special-purpose high speed tension machine in a tension field; placing a leading rope bobbin on a bobbin support; the rope head of the leading rope is lead out through the special-purpose high speed tension machine and line pressing pulleys arranged on the ground. A guide rod type pulley is suspended on a line laying construction position of each base tower; the helicopter drags the rope head of the leading tope and flies over a preset leading rope laying channel. The helicopter flies over the tower so that the leading rope falls into the guide rod type pulley, and the helicopter flies to the next base iron tower. If the bobbin of the leading rope is about to run out, the helicopter hovers; and then the bobbin is changed into a new leading rope bobbin in the tension field, and the helicopter continues to perform flight working until the leading rope goes through the guide rod type pulleys of all the iron towers of a line laying segment. The helicopter flies to an anchor line field at the end of the line laying segment, slowly descends and anchors the leading rope to the ground. According to the invention, a lot of cooperation work by high altitude construction personnel can be reduced so as to greatly raise the security and the construction efficiency.