In order to achieve the goal of ocean-going fishing vessel renewal, transformation and upgrading and gradually realize the specialization, standardization and modernization of ocean-going fishing vessels, by relying on the digital research and development platform of fishing vessels, the optimization design of 320 GT ocean-going double deck trawlers is systematically carried out by means of the main dimensions and main parameters of vessel form, optimization method and comprehensive performance analysis of fishing vessel form, application of energy-saving measures of bulbous bow and stern ball of small and medium sized fishing vessels, optimization and matching study of parameters of fishing vessel engine and propeller, and research on high efficiency fishing machinery hydraulic drive system of trawlers. Through the demonstration and popularization of the vessel form, it is proved that the design of the vessel is reasonable, the supporting equipment is technologically advanced, the layout of the cabin is reasonable, and the comprehensive performance such as seaworthiness, rapidity, maneuverability and safety is obviously better than similar vessels. The energy saving is over 20%, the economic benefits are considerable, solving some key technical problems of vessel form optimization, resistance reduction, energy saving and double deck safety for ocean-going small and medium-sized trawlers subject to the gross tonnage limit, and the application of relevant technical achievements will play an important role in promoting the renewal and transformation of China’s ocean-going trawlers.