This paper briefly introduces The Geometry of Spacetime Structure. Starting from the fundamental logic of the Geometry of Spacetime Structure, it rigorously proves that the Standard Model of particle physics is a necessary corollary of this theory, establishes the characterizing equations for the full spectrum of high-energy particle transient states, and accurately derives the energy levels of all known high-energy particle transient states. Moreover, using only fundamental natural constants, it precisely determines such important natural parameters as the neutron—proton mass difference (1.2933 MeV) and the neutron decay lifetime (879 s). Unlike Quantum Field Theory, the Geometry of Spacetime Structure takes the visible and measurable stable proton and electron as the indivisible fundamental particles of nature with nonzero mass, whose mass, charge, and spin are all intrinsic quantum invariants of the spacetime structure. By employing an intuitive and concise quasi-4-dimensional spacetime motion geometry to reveal the laws of natural change, it not only unifies the fundamental interactions of nature but also unifies the related theoretical systems of physics and mathematics created for the purpose of revealing the laws of nature.