Based on the average atom model, the statistical values of valence electron structure (VES) parameters Δρ′, σ of homophase interface and heterpphase interface had been calculated in Cu-Zn alloy. VES parameters can characterize properties of interface bonding. The effect of Zn in the Cu matrix on the interface strengthening was discussed by the Δρ′ and σ. The calculation results showed that Δρ′ and σ values of homophase interface and heterophase interface of alloy phase were bigger than ones of Cu matrix. It was the essence of interface strenghening. The heterophase interface value σ was smaller compared with the homophase interface value σ under different Zn contents (weight percent). It was the reason that the stability of matrix was superior to that of between matrix and solid solution.