The invention discloses a ro-ro passenger ship construction method. In a section dividing stage: at least one horizontal divide line is arranged along that horizontal direction at least one deck layerin the vertical direction of the passenger-rolling ship; at least one vertical dividing line is arranged at intervals in the vertical direction in the width direction of the passenger ship. In a segmentation phase, at least one lay of deck is vertically spaced apart to provide a horizontal divide line in that horizontal direction, a vertical dividing line is arranged in the width direction of thepassenger-rolling ship, and the passenger-rolling ship is divided into a plurality of segments, each segment contains a plurality of decks, and the segments can be manufactured with the outer plate of the passenger-rolling ship as the bottom surface in the segmentation manufacturing stage, so that the structural strength of the segments is effectively improved.