The structural design of the ocean fishing vessel is mainly based on the Code for Construction of Steel Ocean Fishing Vessels. No calculation of the total longitudinal strength is required for a vessel with length less than 65m. If it is greater than 65m, its wave bending moment is determined by the empirical formula of the merchant ship, but the difference between the fishing vessel and the merchant ship is large, and the environmental load of the fishing vessel in real working conditions is difficult to express easily by the empirical formula. In this paper, considering the actual working conditions of the fishing vessel and the sea conditions, the calculation for the more realistic external load is carried out in order to more accurately calculate the structural stress and deformation of the fishing vessel, achieve the strength assessment and improve the structural design of the fishing vessel. The three-dimensional model of the saury fishing vessel was established by SESAM software, and the finite element analysis of the whole vessel was carried out for three typical working conditions of fishing vessel returning to port, no-load arrival and heeling. The results show that the rear bulkhead of the cab intersects the stern deck and the rescue deck, and the stress at the intersecting bulkhead between the stern deck and the main deck is greater. To this end, it is recommended to focus on these areas of stress concentration when designing a saury fishing vessel, and make a structural transition. In addition, since the machine arrangement is close to the head and tail, the fish tank is placed in the middle of the hull. Considering various typical working conditions, it is recommended to set the ballast tank in the middle to balance its weight center of gravity and reduce the additional bending moment.