Abstract: A novel type of glass fiber reinforced polymer (GFRP) sandwich structure with an improved chevron folded core was obtained through hot-press molding method. The mechanical response and failure mechanism of this structure under compression loading were investigated with FEM simulation and experiment, the process of damage evolution were described with inducing the fiber crushing model, and the obtained stress-strain curves with simulation and experiment are fitted well. Results show that the variation of relative density of structure not only affects the mechanical performance, but also leads the fracture mode changing.