An innovative loudspeaker diaphragm named NCV has been developed. NCV stands for Nano Carbonized high Velocity and is compounded from various polymers with carbon nanotube. NCV is characterized by high propagation velocity, which exceeds titanium, and moderate internal loss like paper. The diaphragm of various sizes can be molded by injection molding according to each frequency range. Loudspeaker systems using NCV diaphragm can reproduce the original sound precisely over a wide frequency range with same timbre.