China's annual output of dried kelp reaches 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 incompatible with China's dominant raft-type parallel culture system. Domestic semi-mechanized harvesting equipment, meanwhile, 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, this study optimizes mechanization-adapted culture modes and innovates key equipment components, developing a miniaturized continuous harvesting system based on long seedling ropes to overcome the efficiency bottleneck of traditional manual harvesting. First, a circuitous series-connected raft system for long seedling ropes was constructed, integrating 300m continuous seedling ropes with 16mm-wide quick-release buckles. This series structure preserves traditional culture density while facilitating reliable connection and rapid separation between seedling ropes and rafts. Following a modular design approach, 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 the continuous mechanized harvesting equipment. The stripping-cutting tool structure was innovatively optimized: with an outer blade diameter of 120mm and inner blade diameter of 45mm, the allowable heave angle of 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 tool's maximum equivalent stress was 141.14 MPa, far below the yield strength of its material, confirming structural strength reliability. Coupled with an umbrella-spoke-shaped seedling rope storage device (300m capacity), stable and continuous mechanized harvesting of entire rafts was realized. Comprehensive sea trials 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 to 36 minutes, 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-stop and high manual assistance intensity associated with traditional equipment. The system enables integrated operations from seedling rope separation, continuous dragging, stripping-cutting harvesting to seedling rope storage. This research breaks through the technical bottlenecks of poor raft adaptability and low harvesting continuity in kelp mechanized harvesting, 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 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 mechanized harvesting of other large algae, contributing to the intelligent upgrading of marine aquaculture equipment.