The invention discloses a marine cable laying method and a cable laying system, and belongs to the field of marine engineering equipment. A plurality of nodes with one unit distance between every twonodes are additionally arranged between a cable laying line. When a cable laying boat, a first positioning boat and a second positioning boat are located at the first node, the first positioning boatmoves forward one unit distance, the second positioning boat moves forward two unit distance, and the first positioning boat and the second positioning boat move back one unit distance, the cable laying of one unit distance is performed according to the position forward of the first positioning boat, after that, the two steps that the first positioning boat is moved forward three unit distances for anchor positioning, the second positioning boat is moved back one unit distance and the cable laying ship performs cable laying according to the positioning of the second positioning boat and the first positioning boat is moved forward three unit distances for positioning, the first positioning boat is moved back one unit distance and the cable laying ship performs cable laying according to thepositioning of the first positioning boat are performed alternately. In this process, the cable laying ship only needs to carry out cable laying work and does not need to move back and forth repeatedly to achieve the purpose of cable laying, and the problem of low efficiency of submarine cable laying is solved.