In this paper we calculated the electronic structures of Cu4, Cu3Zn and Zn4 clusters using the SCF-Xα-SW method. Along with the orbital energies, the charge distribution and fractional principal partial wave character of all relevant orbitals were also calculated. The results are consistent with the band structures and the experimental data of the corresponding bulk crystalline solids, and show that the cluster approach in conjuction with the SCF-Xa-SW method is not only an effective means to study impuity problems but also a useful method to study ordered alloys and disordered alloys, such as n-brass.