The mechanical property, electronic structure, and optical properties of tetragonal perovskite PbTiO3 and Ni, Cu, Zn-doped PbTiO3 were studied by first principles. The mechanical property calculations show that Ni-doped PbTiO3 exhibits the highest values for volume modulus, shear modulus, and elastic modulus among the three doping systems. Notably, the Ni-doped system also has the highest Debye temperature. The G/B ratio represents the material’s brittleness and toughness, which is highest for Zn-doped PbTiO3, indicating the highest degree of chemical bond orientation. The G/B range for Ni and Zn-doped systems is 0.56