Abstract In this paper, we summarized the concepts and units of magnetic field, magnetic induction field, magnetic moment, magnetization, magnetic susceptibility in the research of molecular magnetism. The conversion of these physical quantities between the SI and EMU unit system is clearly demonstrated. Moreover, the application of fundamental equation in molecular magnetism, Van Vleck equation as well as the Brillouin function to calculate the mole magnetization and mole magnetic susceptibility is also discussed.
