We employed a quantum simulation model and a new computational algorithm we developed recently to study the magnetism of an assumed DyNi2B2C nanoparticle consisting of an inner core and an outer shell of complicated crystal and magnetic structures. Our theoretical results obtained with the new simulation model are reasonable physically, and the computational speed with the new algorithm is faster than the micromagnetism and MonteCarlo approaches, which have been popularly utilized by most researchers worldwide for many years.