Abstract: Glass fiber reinforced resin composite(GRP) sandwich panels with PVC foam or Balsa wood as core material are widely used in ship construction and ocean engineering. Flexural behaviors of hybrid joints of sandwich panel-steel plate which subjected to static and fatigue loads respectively, were investigated with both numerical and experimental methods. Different parameter sets of hybrid joint specimens were designed and fabricated. Static and fatigue four-point bending experiments were implemented to study the bending strength, stiffness and failure modes of joints. ABAQUS and MSC. Fatigue softwares were also adopted to simulate their failure characteristics. The influences of filler material, geometric length of filler and the inserted length of steel plate on the bending performance of the joint were respectively assessed. The results show that failure occurs near the filler area of joints under bending load, and failure mode mainly depends on different filler parameters. Extending the steel end to filler area can obviously improve bending performance of joint, as well as adopting Balsa wood as filler material. All specimens are failed before 10⁶ cycles in the larger fatigue load case, while in the lower fatigue load case, all the specimens are nearly intact after 10⁶ cycles and their residual strengths are quite close to their static ultimate strength. It is indicated that fatigue cycles with smaller loading amplitudes have little influence on their loading capacities.