Using molecular dynamics (MD) simulations, we explore the effects of body defects on the elastic and plastic properties of Cu nanowires along < 100 >, < 110 > and < 111 > crystallographic orientations under tension, respectively. Such a body defect is a vacuum sphere localized at the center of nanowire with a radius changing from 1.80 to 10.83 . Our calculations illustrate that body defects have a little influence on the elastic properties of Cu nanowires, whereas they have a great influence on the plastic properties of Cu nanowires, showing orientation dependence. In < 100 > oriented nanowire, the existence of body defects leads to a decrease in the plastic property of nanowire, whereas it plays an opposite role in both < 110 > and < 111 > oriented nanowires, resulting in an improvement in the plastic properties of nanowires. Our findings provide an effective method to improve the plastic properties of Cu nanowires, which could be widely applied for the design of nanodevices.