Carbon nanotubes(CNTs) are largely synthesized on Fe catalysts by catalytic chemical vapor deposition. The various shapes and compositions of these nanostructure CNTs were obtained by controlled parameters such as the reaction temperature, gas-mixing ratio. The influence of these parameters is investigated, together with observations of the produced materials after the purification processes. A diameter of CNTs, range from 2 to 10 nm, closely correlated with the size of the catalyst particle found attached to the tube end. The yield of CNTs was estimated to be 88.5 % and the purities of CNTs thus obtained were more than 80 %. The experimental results were documented with field emission scanning electron microscopy and raman spectroscopy and transmission electron microscopy, both before and after the purification.