Super-plasticity of single-crystal beta-SiC [111] nanowires for > 200 % elongation was observed by in situ axial-tensile experiments in a scanning electron microscope. The SiC nanowires were characterized by a bamboo-like structure appearing as the 3C structured segments intergrowth along the nanowire. The axial localized plasticity and super-plasticity are suggested to result only from the 3C segments, through dislocation generation, propagation and amorphization in contrast to the highly defected structural segments that conduct elastic-deformation only, owing to the lack of slip systems. These results provide key information for understanding the mechanical behavior of SiC nanowires.