Abstract: arbon nanometer materials with small size, high purity and various structures, synthesized by laser ablation have been widely applied in many fields. The processes of laser ablation in gases and liquids are discussed. Different physical chemistry phenomena exist in different media. The plasma zone generated by laser ablation of a solid target under a liquid is confined by the liquid. The temperature, pressure and density of the laserinduced plasma zone at the solidliquid interface are higher than those in a gaseous medium, which is suitable for the growth of nanocrystals, especially metastable nanocrystals such as diamond and carbon related materials. Carbon nanotubes could be prepared in gaseous and liquid media using a pulsed laser. Carbon nanotubes tend to grow in a gas, and nanodiamonds in a liquid. The size of nanodiamonds obtained from the graphite target is larger than that from a graphite suspension. The pulsedlaser irradiation of a graphite suspension can also be used to prepare linear carbon (carbyne).