Wood compression process was innovatively introduced as a pre-treatment method to birch into the fabrication of biomorphic silicon/silicon carbide (Si/SiC) ceramic with high density. Firstly, birch blocks were compressed to the density in the range of 0.85-1.00g/cm3. Secondly, both birch blocks and compressed birch blocks were carbonized at 1200°C to get carbon templates. Lastly, carbon templates were infiltrated with liquid silicon to obtain biomorphic Si/SiC ceramics. The effect of compression process on the density and microstructure of both carbon template and ceramic was investigated. The results show that the maxium density of biomorphic Si/SiC ceramic from compressed birch is 3.01g/cm3, whereas the density of the ceramic from birch is only 2.80-2.89g/cm3. So the compression process was an effective method to increase the density of biomorphic Si/SiC ceramic.