the bait used in crab cage fishing boat needs to go through ice breaking separation, cutting, box filling, cage plugging and other processes, with low efficiency and high labor intensity. In order to improve the production efficiency of crab cage fishing boat, automatic use of bait is needed. In this paper, an automatic assembly line production scheme for bait use is presented, and the structural design modeling and principle analysis of the assembly line are carried out by Pro / Engineer Wildfire 5.0. The design of assembly line PLC control ladder diagram program is completed with GX works3 based on Mitsubishi FX5U series PLC, and on-line simulation test is carried out on the software. The results show that the structural design of the assembly line theoretically meets the requirements for automatic use of bait for crab cage fishing boat. The design of the control system conforms to the action sequence control of the assembly line, and the port runs normally without any error prompt. The production scheme of the assembly line provides the conditions for automatic use of bait for crab cage fishing boat, and also breaks the traditional feeding method of bait for crab cage, changing the internal feeding mode into the external squeezing type. The design of the control system has laid a theoretical foundation for the actual production and application of the automatic cutting box filling and cage plugging assembly line of bait for crab cage fishing boat.