In this paper,the polarization mechanism of the silicon nitride ceramics are studied by using dielectric physics and mathematical methods.The contribution to the dielectric constant of silicon nitride is divided into electronic displacement polarization,ionic polarization and thermal ion polarization,and explain the gap of dielectric constant between the α-Si3N4 and β-Si3N4.Understanding the dielectric loss is produced by relaxation loss and conductivity loss,then analyzing main function they played in different temperature,calculate dielectric constant temperature coefficient.Finally,modeling the influence factors and changes with temperature of the dielectric constant and dielectric loss which can fit the experiment data well.