The quasiparticle density of states (DOS), the energy gap, the superfl
uid density rho(s), and the localization effect in the s- and d-wave s
uperconductors with non-magnetic impurity in two dimensions (2D) are s
tudied numerically. For strong (unitary) scatters, we find that it is
the range of the scattering potential father than the symmetry of the
superconducting pairing which is more important in explaining the impu
rity dependences of the specific heat and the superconducting transiti
on temperature in Zn doped YBCO. The localization length is longer in
the d-wave superconducting state than in the normal state, even in the
vicinity of the Fermi energy.