Nanoscale tungsten oxide, as a functional semiconductor with unique physical and chemical properties, is widely used in environment, energy, life science and information technology fields. Based on the application of first-principles study in nanoscale tungsten oxide, the functions of theory calculations are reviewed in the paper. Firstly, the development and basic theory of the first principles and density functional theory are illustrated based on quantum mechanics. Then, the commonly related software in such field of semiconductors, such as MS (Materials studio) and VASP (Vienna ab initio simulation package) are introduced. Furthermore, the recent study of the first-principles on tungsten oxide in terms of electronic structure, interaction of materials, molecular thermodynamics, and so on, is clarified. Finally, the existing problems and future developments of theory calculations used in the field are summarized and prospected.