Abstract: Based on the ε＇ （ω） and complex dielectri definition of di function ε （ω） dielectric function. Calling ε＇（ω） ＂ complex electric function and the meaning of its imaginary part, the function are compared and analyzed. The function ε＇（ω） is not the complex dielectric function.Calling ε＇（ω）＂complex dielectric function＂ is not proper.

Key words: dielectric function, conductivity, Maxwell＇s equations