The disclosure relates to a method for measuring a dielectric tensor of a material. Firstly, a partial conversion matrix Tp and a transmission matrix Tt are determined by a predetermined initial value ε(E) of the dielectric tensor of the material to be measured, thereby obtaining a transfer matrix of an electromagnetic wave on a surface of the material to be measured by the partial conversion matrix Tp, the transmission matrix Tt, and an incident matrix Ti, a theoretical Mueller matrix spectrum MMCal(E) of the material to be measured is determined by the transfer matrix Tm. A fitting analysis is performed on the theoretical Mueller matrix spectrum MMCal(E) and a measured Mueller matrix spectrum MMExp(E) of the material to be measured to obtain the dielectric tensor of the material to be measured.