Abstract:The mechanical properties and the extensional deformation of the single-crystalline Cu nanowires with FCC crystal lattice are analyzed. The elastic modulus and yield strength in three different directions of <100>, <110> and <111> are investigated by the quasi-static classic MD (Molecular dynamics) simulation of the nanowires under tension at room temperature. The discuss about the stress-strain relation and the tension -deformation mechanism of the nanowires, which in term of the structure evolution and the resolved shear stress,is carried out. It is found that the <111> Cu nanowires is highest in strength, while the <110> is worst, and the <100> is best in ductility, the <111> and <110> is similar poor Nanowires have different mechanical properties in different tensile directions