Abstract: Original cellular automaton capture rule was modified and applied to simulate dendrite growth during solidification process in welded molten pool of nickel-based alloy.The results show that the competitive growth between dendrites with different crystallographic axes orientations is intense.The grains,whose crystallographic axes orientations are in accordance with the direction of largest temperature gradient,have a fast growth speed and overgrow other grains,so that they can keep growing during solidification process.Meanwhile,solute concentrates in the residual liquid in the closed zone among dendrites and dendrite arms,which can lead to severe grain-boundary segregation after solidification process.