From the perspective of the combination of macroscopic numerical simulation and microscopic EBSD experiment,the weld grain growth and its effect on the mechanical properties of the laser welding joint for 1060 aluminum alloy are studied. The results show that the grain size reduces as the heat input decreases,and dense equiaxed crystals gradually generates in the center of the weld,which will enhance grain boundary strengthening effect and the plasticity of the weld metal zone;in the process of heat input reduction,the shape of the molten pool transitions from elliptical shape to teardrop shape. The growth shape of the columnar crystal changes from bending to vertical under the influence of the columnar crystal. The growth direction of columnar crystals is consistent with the heat flow distribution and perpendicular to the end of fusion boundary,and the angle between the growth direction of columnar crystals and the weld center line increases as the heat input decreases. The characteristic of columnar crystal anisotropy makes its tensile strength higher when it is close to the tensile force;with small heat input,the weld grain will produce a obvious cubic texture,which helps to improve the plasticity of the weld metal zone;the tensile strength of the joint gradually increases when the heat input reduces from 120 J/mm to 75 J/mm,and when the heat input reduces to 58 J/mm,the welding speed is too fast,which will produce obvious pore defects,and the tensile strength of joint declines comparing with that when heat input is 75 J/mm.