In order to enhance the ocean exploration, a small and compact lifting system installed on the ship for easy transportation is designed. According to the relevant work and design principles, the mechanical structure of A-type gantry is modeled by using the modeling software SolidWorks. The finite element analysis software of ANSYS Workbench is used to analyze the deformation and stress of the main bearing part of A-type gantry, the connection part of fixed pulley of gantry and the pin shaft at the connection of gantry and frame. The results show that when the load is 85 000 N, the maximum deformation and stress of the A-type gantry is at the beam, and the maximum stress is 260 MPa, which meets the requirements of the selected material; the maximum deformation is 17.5 mm, and the deformation only accounts for 0. 643% of the total length, which meets the design requirements. The maximum stress is 132.45 MPa and the maximum deformation is only 0.054 mm at the joint of the pin shaft at the pulley and the cross beam, the maximum stress is 130.41 MPa at the two sides of the pin shaft at the joint of the gantry and the frame, and the maximum deformation is 0.05 mm in the middle of the pin shaft; Both of them meet the performance requirements of the selected material 45 steel, and the small deformation has no effect on the use. The verification results show that the design is feasible, and the model of some parts is established.