Abstract: Water vapor-assisted chemical vapor deposition was used to prepare vertically-aligned carbon nanotubes (ANTs) on a quartz substrate by using ferrocene as a catalyst precursor and xylene as a carbon source. The morphologies of the ANTs were investigated by TEM and SEM. Results showed that under optimized growth conditions ANTs were grown on the substrate with an area of 60×140 mm2 and a thickness of 2.05 mm. The ANTs emit strong white light under microwave radiation, indicating that they are a potential microwave absorption material.