The modification of SrTiO ₃materials by doping Nb ⁵⁺ions in B-site is studied through using the first-principles method to calculate the electronic structure, optical properties, mechanical properties and thermal properties at different Nb ⁵⁺doping concentrations. The calculation results show that as the doping content of Nb ⁵⁺increases, the lattice parameters increase. After being doped with Nb ⁵⁺, SrTiO ₃changes from an indirect band gap compound into a direct band gap compound. Doping Nb ⁵⁺can reduce the reflection coefficient, absorption coefficient, and energy loss of SrTiO ₃material, which can be used to modify its optical properties. Additionally, the brittleness of SrTiO ₃material is improved through doping Nb ⁵⁺. As the doping content of Nb ⁵⁺increases, the elastic modulus of the material hardly changes, the shear modulus and Young's modulus decrease, the Poisson's ratio increases, and the Debye temperature decreases, and both the lattice thermal conductivity and the theoretical minimum lattice thermal conductivity decrease as well.