The concept of electron spin has a broad application prospect. However, after a century of efforts, the essence and specific form of electron spin have not been revealed. The reason is probably that it is constrained by the concept of point particle material structure. In order to solve the problem, one way to initiate the quantum mechanics revolution on the concept of material structure is to establish the concept of wave element material structure. Assuming that the composition of electrons is waves, the inherent motion of electrons (the spin of free electrons) is "the rotation of mass equivalent to the energy of waves". This rotation is not the rotation of a sphere, but similar to the rotation of a ring-shaped substance along a ring. This assumption breaks the concept of point particle structure. According to it, the angular kinetic energy and spin magnetic moment of electrons can be accurately calculated by classical force electrodynamics method. Other applications are also very successful, which has led to the revolution of quantum mechanics and material structure theory.