We present an orthogonal tight-binding (TB) potential model for W/Cu binary systems. This model can reasonably predict the electronic structures, elastic properties, and thermodynamics properties of W/Cu systems. Furthermore, by performing the TB Monte Carlo simulations and the TB molecular dynamics simulations, we find that (1) the W(110) surface in the fusion reactor exhibits pre-melting behaviors, (2) W and Cu atoms in a W/Cu binary system prefer to form single element domains, and (3) the interface between a W domain and a Cu domain degrades the transport property of the heat in a W/Cu system significantly.