The frequency range of δ dispersion of biological muscular tissue was studied and the fact that the δ dispersion occurs over a wide frequency range was verified.The frequency ranges were roughly evaluated by changing four relaxation time parameters by using the four-order Cole-Cole model.Afterwards,the dielectric constants and their increments within the frequency ranges were numerically calculated.Base on the increment of the dielectric constants,the precise frequency range of α,r,δ and γ dispersions in muscular tissues were evaluated.The results showed that the α dispersion of muscular tissue presented the most narrow frequency range compared with any other type of dispersion,the corresponding increment of dielectric constant was larger than that of any other dispersion.The frequency range of β dispersion was wider than that of α dispersion.However,the increment of the dielectric constant of β dispersion was smaller than that of α dispersion.The δ dispersion frequency range was wider than those of α and β dispersions.And the corresponding increment of dielectric constant was smaller compared with those of α and β dispersions.The γ dispersion increment of dielectric constant was the narrowest.