Abstract: 3D spacer grille fabric composites were developed in this paper. Its mechanical characteristics under flatwise compressive and shear loads were analyzed, and the effects of pile distance, pile height and foam on the mechanical properties were investigated. The results indicate that the flatwise compressive and shear properties of 3D spacer grille fabric composites decrease with the pile distance increasing. After filling the foam, synergy effects between the piles increase with the increace of pile distance. The failure modes of heavy-thickness spacer fabric composites are pile instability under flatwise compression, and fractured at the joint of pile and facesheet under shear load.