Abstract: Nomex honeycomb sandwich composites with different core thickness were prepared using NRH-2-48 aramid paper as core and carbon fiber laminates as panels. The effect of core thickness on compressive property was studied by compression testing, and the relationships of core thickness with buckling load and compressive breaking load were investigated. The results show that with the increase of core thickness, the buckling load and the breaking load of the composite increased. When the buckling load of composites was as high as the breaking load of the panel, the core thickness was the best.