Abstract: Superplasticity of the pulse elect rodeposited SiC_P / Ni nanocomposite was investigated by tensile test s.St rain rates range f rom 8.3 ×10 ^-4 to 5 ×10 ^-2 s ^-1 , and the selected temperatures are 410 ℃and 450 ℃. A maximumelongation of 836 % was obtained at the st rain rate of 1.67 ×10 ^-2 s ^-1 and temperature of 450 ℃. Surface morphology , f racture surfaces and deformed microst ructure were observed by SEM and TEM. The deformation mechanismwas analyzed. SiC has a favorable effect on the superplasticity of the material by enhancing the microst ructural stability. A low volume f raction of cavity was helpful to obtain high elongation. The main deformation mechanisms aredislocation accommodated grain boundary sliding and dislocation slip plasticity when the grains grow to micro size.