This chapter discusses the process control of carbon nanotube formation using radio frequency (rf) glow-discharge plasma in strong magnetic field. The formation of uniform and well-aligned multi-walled carbon nanotubes (MWNTs) is investigated by controlling rf glow-discharge plasmas in strong magnetic field. When the magnetic field is weak, the MWNTs growing directly on the rf electrode are deformed by the bombardment of the high energy ions generated by the large sheath electric field in front of the rf electrode. When the strong magnetic field is applied the MWNTs are observed to be well aligned and not deformed. These results can be explained by the fact that the ion bombardment energy reduces the existence of the large sheath electric field, which is caused by the magnetization of the ions in the strong magnetic field.