Copper has several desirable characteristics, including being lightweight and having excellent mechanical, electrical, and thermal properties. Its remarkable resistance to corrosion and cheap cost make it essential for a wide range of industrial uses, such as electrical cables, switches, transformers, telephones, automobiles, and warship hull components. This study investigates the behavior of copper atoms under nano-indentation using a large-scale atomic/molecular massively parallel simulator. Nano-indentation simulations were performed at a velocity of 100 Å/ps. For the first time, this study reveals how the BCC crystal structure and dislocation evolve during indentation and demonstrates how hardness varies with changes in the radius of a spherical indenter tip. Crystal evolution and dislocation mechanisms were analyzed using several parameters, including indentation force–displacement curves, radial distribution function, atomic percentage change with indentation depth, dislocation density, total energy variation with penetration, and visualizations of dislocation during the nano-indentation process in copper. The outcomes of this work offer meaningful insights for researchers focused on material design and performance optimization in engineering applications.