(1) Perfect diamagnetism was found in 1933.

(2) Based on the perfect diamagnetism of superconductor and electromagnetic theory, magnetic field force is used to do work mechanically.

(3) The hard X-ray signal is observed while the diamagnetism signal appears.

(4) A classical statistic method of interpreting the diamagnetism is introduced.

(5) According to the classic physical theory, the mechanism of magnetic medium diamagnetism was explained.

(6) In the experiments of measurement and software compensation of diamagnetism, it is found that stray fields mainly come from the vertical field, plasma current and eddy current.

(7) In this paper I have strictly derived these formulae about Landau Diamagnetism by using the theory of statistical mechanics of ideal Fermi system and Laplace transformation.

(8) This essay, Starting from the Calculation of the atomic magnetic moment, approaches the quantum theory of Paramagaetism and diamagnetism by applying quantum mechanics perturbation theory.