Atomic-scale investigations on the surface diffusions of Pb adatoms on uniaxially strained Cu(111) were performed using molecular dynamics simulations and ab initio calculations methods. Tensile strains in [ 1 1 ¯ 0 ] reduced the surface diffusion coefficient, while the [112] strains increased the diffusion coefficient until the Cu(111) substrate was elongated 4% uniaxially. The surface diffusion energy barriers for the three different paths: [ 1 1 ¯ 0 ] , [112] and [ 2 1 ¯ 1 ] , were calculated using ab initio calculations. The energy barrier only for the [ 1 1 ¯ 0 ] direction was increased when tensile strain in the [ 1 1 ¯ 0 ] direction was applied, while the [112] strain decreased the energy barriers for all three diffusion paths. The [ 1 1 ¯ 0 ] strain altered the easy surface diffusion direction from the x-direction to the y-direction, while the [ 2 1 ¯ 1 ] strain created isotropic diffusion coefficients in lateral directions.