This study aimed to tackle the key challenges in offshore aquaculture, including insufficient safety assurance and incomplete technical and procedural systems, and to verify the feasibility and effectiveness of high-density farming technology for Large Yellow Croaker (Larimichthys crocea) using an aquaculture on board mode. A three-month farming experiment (from July 9 to October 24, 2025) was designed, utilizing the self-developed "Yuji No.1" towable, closed aquaculture mobile farming platform as the core experimental facility. The experimental tank provided an effective water volume of about 900 m³, stocked initially with Larimichthys crocea averaging 311.60±68.56 g in weight, at a density of 15.37 kg/m³. Standardized farming operation procedures were implemented through the platform's integrated systems, including fish-friendly flow field regulation, automatic dissolved oxygen feedback, intelligent lighting, and vision-based feeding. Water quality parameters (e.g., temperature, dissolved oxygen, ammonia nitrogen) and fish behavior were monitored, and fish growth performance and health status were measured periodically. During the experiment, the aquaculture water environment remained stable, with key environmental factors (flow velocity 0.5-1 bl/s, dissolved oxygen 8-10 mg/L) within the suitable range for Larimichthys crocea. At the end of the experiment, the average weight of the fish reached 675.82 g, with an average monthly weight gain of 104.1 g, a cumulative survival rate of 95.05%, and the farming density increased to 31.65 kg/m³. The feed conversion ratio was 1.15-1.31. The fish maintained a stable health status, with no large-scale disease outbreaks occurring. This research verifies that the aquaculture on board system and its supporting technologies can achieve high-density, high-efficiency, and high-survival-rate farming of Larimichthys crocea, providing reliable technical support and an engineering demonstration for the promotion and application of industrialized offshore aquaculture models.