Abstract: Trapezoidal lattice-web reinforced foam core sandwich composites with different structural parameters were designed and manufactured by the vacuum assisted resin infusion (VARI) process. The failure modes and mechanical properties of the sandwich panels in flatwise compression loading were studied experimentally. Also, the effects of structural parameters (specimen size, lattice-web angle, lattice-web thickness) on specific compression strength, specific compression modulus and specific energy absorption were investigated. The results show that the main failure modes of the lattice-web reinforced sandwich panels are the fracture and buckling of lattice-web, and the synergistic enhancement effect between foam core and lattice-web is revealed. Compared with the control specimen, the specific compression strength, specific compression modulus and specific energy absorption of the sandwich panel with 60° lattice-web increase by 89.4%, 137.9% and 45.2%, respectively. The compression properties increase with the increase of the angle and thickness of lattice-web. The conclusions above provide reference for the design and application of lightweight sandwich composites in the ship and ocean engineering.