The invention relates to preparation technology for carbon nano-tubes, in particular to a method for preparing a carbon nano-tube macroscopic body, which is suitable to prepare a macroscopic body of single-walled, double-walled or multi-walled carbon nano-tubes. The method comprises the following steps: uniformly mixing an iron (cobalt or nickel)-containing catalyst and a sulfur-containing growth promoter in a gaseous state; then allowing the mixture to enter a reaction zone to generate the carbon nano-tubes; floating the generated carbon nano-tubes in a gas phase; allowing the generated carbon nano-tubes to enter a low-temperature area along with an airflow direction; and filtering and depositing on a porous material so as to form a carbon nano-tube macroscopic body formed by piling multi-layer carbon nano-tube films. The method can control microscopic structures of the carbon nano-tubes, the bulk density of single-layer carbon nano-tube films and the thickness of the macroscopic body by simply adjusting process parameters; and the method has the characteristics of high product yield, high purity and low cost.