Tensile properties of an electric brush-plated nanocrystalline Cu with an average grain size of 59nm were investigated at different strain rates. This nanocrystalline Cu exhibits an excellent combination of strength and ductility with its ultimate tensile strength increasing from 635MPa to 1000MPa and total elongation decreasing from 15.8% to 9.9% as strain rate increases from 10−4s−1 to 1s−1. Analysis based on the characterization results of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and general area detector diffraction detection system (GADDS) on the as-brush-plated and deformed NC specimens revealed that the excellent combination of strength and ductility arises from the enhanced dislocation strain hardening ability and the improved deformation accommodation role played by GB sliding.