Einstein's theory of relativity is a symbol of his lifelong career. In his paper entitled "On Electrodynamics of Moving Objects" published in 1905, he put forward the special theory of relativity completely, which largely solved the crisis of classical physics at the end of 19 and promoted the revolution of the whole physics theory. At the end of 19, physics is changing, and new experimental results are impacting the classical physics system established since Galileo and I Newton. The older generation of theoretical physicists, represented by H.A. Lorenz, tried to solve the contradiction between old theory and new things on the original theoretical framework. Einstein believes that the way out lies in fundamentally changing the whole theoretical basis. According to the relativity of inertial reference system and the invariance of light speed, he reformed the basic concepts of time, space and motion in classical physics, denied the existence of absolute static space and denied the absoluteness of the concept of simultaneity. In this system, the scale of motion should be shortened and the clock of motion should be slowed down. One of the most outstanding achievements of special relativity is to reveal the relationship between energy and mass. Mass (m) and energy (e) are equivalent: e = mc2 is a corollary of relativity. This can explain why radioactive elements (such as radium) can release a lot of energy. Mass-energy equivalence is the theoretical basis of atomic physics and particle physics, which satisfactorily explains the long-standing problem of star energy. Special relativity has become a basic theoretical tool to explain high-energy astrophysical phenomena.