Abstract: The rapid solidification process of NiCr alloy produced by micro arc plasma has an important influence on the microstructure and properties of structural parts manufactured by additive. In this paper, molecular dynamics (MD) was used to simulate the temperature field and the growth of equiaxed grains in the process of micro arc plasma additive forming NiCr alloy components. The results show that the NiCr alloy exhibits amorphous solidification at cooling rates of 3.38 K/ps and 0.675 K/ps, and the NiCr alloy spontaneously nucleates and grows at cooling rates of 0.077 5 K/ps, realizing equiaxed solidification and crystallization. The simulation results are in good agreement with the phase field method and the electron micrographs of equiaxed region, which provides a theoretical basis for the study of microstructure evolution of NiCr alloy fabricated by micro arc plasma additive manufacturing.