Carbon Nanotubes are a class of all-carbon molecules with incredible single-molecule properties, including strengths 100 times greater than steel at only 1/6 the weight and current carrying capacities three orders of magnitude higher than conventional metals. However, both the mechanical and the electrical properties of carbon nanotube materials can be reduced to levels that are worse than conventional materials when these molecules are arranged into macroscopic scaffolds having length scales much larger than that of carbon nanotube. Obviously, the best solution for this problem is to grow extremely long CNT arrays, so the researchers have taken significant efforts in understanding the growth termination mechanisms and finding a rational route to improve CNT array growth. In the first part of the talk, the growth termination mechanisms of carbon nanotube arrays grown by chemical vapor deposition method using the supported catalysts will be dealt with. Then, in the last part of the talk, the direct spinning of carbon nanotubes into long macroscopic fibers will be introduced, which is much more practical approach. Current issues to prevent from synthesizing strong carbon nanotube fibers in terms of CNT growth by floating catalyst chemical vapor method and several approaches we are attempting to solve the issues will be thoroughly discussed.