In the view of ship lightweight,a new y-shape hybrid joint was proposed,consisting of glass fiber reinforced plastic,PVC foam,resin and steel,to solve the connection problem for lightweight components to metallic structures.The main emphasis of this study was placed on the mechanical behavior of the new hybrid joint between a composite sandwich superstructure and a steel main hull.According to the design principles and mechanical properties of composite structures,the compression tests were investigated.And the ultimate bearing capacity and damage modes were examined.Based on the experiments,a new numerical simulation method was used to analyze the mechanical and physical characteristics of the new joint.The numerical predictions showed a very good correlation with the experiment results,which validated the reliability of the numerical simulation method.The mechanical behavior of the y-shape hybrid joint was evaluated through linear and nonlinear numerical method.The study found that the adhesive resin between steel plate and glass fibre reinforced plastic plate is weak spot,and the change of geometry and material is an effective way to improve the performance of the composite to steel hybrid joint,which supports the optimization design and practical application of ship lightweight adhesive bonded joints.