In this paper, molecular dynamics simulations are used to study the structure of Ni-based single superalloys with a 100 Ni/Ni3Al grain boundary. Tw o differe nt initial models are relaxed at 300K using Finnis-Sinclair-type potential. Our simulations reveal that the misfit energy due to the difference of their lattice constants is released not by long-range lattice misfit but by forming dislocati ons in local regions. Due to the surrounding differences of Ni3Al pha se in Ni-based phase, the dislocations formed are different.