An exemplary method for producing carbon nanotubes includes the following steps. First, a reaction chamber is provided. The reaction chamber defines a reaction region therein. Second, a substrate having a catalyst layer formed thereon is provided. Third, the substrate is disposed in the reaction chamber. Fourth, a carbon-containing reactive gas is introduced into the reaction chamber so as to grow carbon nanotubes using a chemical vapor deposition method. The substrate is moved along a direction opposite to a growth direction of the carbon nanotubes whilst growing the carbon nanotubes, whereby tips of the carbon nanotubes are kept in the reaction region while the substrate is moved.