The first-principles calculations were performed to investigate the electronic structure and the optical properties of the MgxTi(1-x)H2 (x = 0.25, 0.5, 0.75, 0.875) systems with different Ti contents by the pseudopotential plane-wave method based on density functional theory. The electronic densities of state reveal that the MgxTi(1-x)H2 hydrides exhibit metallic characteristics by adding Ti atom to MgH2 hydride. It originates from the increasing of the valence electrons at Fermi level and the vanishing of band gap near Fermi level. The bonding nature of the hydrides was investigated by analyzing the charge distribution of MgxTi(1-x)H2, and it shows stronger covalent bonding between Ti and H than between Mg and H. The calculated results from the optical properties of MgxTi(1-x)H2 show that Ti content in MgxTi(1-x)H2 systems has an important influence on the optical properties near visible light energy region. For the lower Ti content in MgxTi(1-x)H2 such as x=0.875, it is not favorable to improve absorption over the whole visible region. Whereas the reflection is high for the higher Ti content, such as x=0.25. The calculated results provide a theoretical basis for preparing Mg-Ti-H photoelectric materials with excellent absorption and photoelectric conversion efficiency over the whole visible region.