In China, the annual output of dried kelp is as high as 1.86 million tons; however, the harvesting process still relies heavily on manual labor, leading to low per capita efficiency and high labor intensity. Although foreign mechanized harvesting equipment exists, it is designed for long-line culture modes and is incompatible with the raft-type parallel culture system prevalent in China. The development of domestic semi-mechanized harvesting equipment faces challenges, such as poor raft adaptability and insufficient harvesting continuity, highlighting the need for synergistic innovation in both culture modes and equipment. To address these issues, we optimized mechanization-adapted culture modes and innovated key equipment components to develop a smaller-scale continuous harvesting system based on long seedling ropes, thus overcoming the efficiency bottleneck of traditional manual harvesting. First, a circuitous series-connected raft system for long seedling ropes was constructed by integrating 300 m continuous seedling ropes with 16 mm-wide quick-release buckles. This series structure preserves traditional culture density while facilitating reliable connections and rapid separation between the seedling ropes and rafts. Following a modular design approach, the core components (e.g., rectangular guiding devices, inclined conveyors, and low-damage stripping-cutting tools) were integrated with a hydraulic centralized control system, enabling single-person operation of continuous mechanized harvesting equipment. The stripping-cutting tool structure was innovatively optimized, with an outer blade diameter of 120 mm and inner blade diameter of 45 mm, and the allowable heave angle of the seedling ropes was increased to 55°. Dynamic simulation analysis using Ansys LS-DYNA software for emergency scenarios (e.g., hanging rope entanglement) revealed that the maximum equivalent stress was 405.04 MPa, far below the yield strength of the material, confirming structural strength reliability. Coupled with an umbrella-spoke-shaped seedling rope storage device (300 m capacity), stable and continuous mechanized harvesting of the entire raft was achieved. Trials of the equipment at a kelp harvesting site demonstrated that at a harvesting line speed of 9.36–14.82 m/min, the system achieved 100% kelp-harvesting completeness with no seedling rope breakage. Single-raft harvesting time ranged from 27‒36 min, and the per capita harvesting rate reached 2 t/(h·person), twice that of traditional manual labor. Only four workers are required to complete the entire process without heavy physical labor, addressing the issues of frequent start–stops and high manual assistance intensity associated with traditional equipment. The system enables integrated operations such as seedling rope separation, continuous dragging, stripping-cutting harvesting, and seedling rope storage. The novel harvesting system proposed in this study addresses the technical bottlenecks of poor raft adaptability and low harvesting continuity by establishing a collaborative solution for mechanization-adapted culture modes and equipment. The modular design accommodates operational needs across different scenarios, and the doubled efficiency effectively alleviates labor shortage pressures, providing equipment support for the large-scale promotion of mechanized harvesting in China's major kelp-producing regions. Beyond the kelp industry, the modular design concept and low-damage harvesting technology offer references for the mechanized harvesting of other large algae, contributing to the intelligent upgrading of marine aquaculture equipment.