In this paper, electronic structure, energy band structure and electronic density in cubic phase for semi-conductor MgSe are studied using WIEN2k package. This employs the Full Potential-Linearized augmented Plane Wave (FP-LAPW) method in the framework of Density Functional Theory (DFT) with generalize different approximations. The results showed a band gap of 2.4 eV at Γ point in the Birrouin zone. The calculated band structure and electronic structure of MgSe agree with the previous experimental and theoretical reports, as do the charge distribution indicated that the bond the Mg and Se is ionic with the one of the properties MgSe.