The dielectric properties of SiNx films,which were deposited at low temperature by microwave electron cyclotron resonance plasma chemical vapor deposition,have been investigated.The frequency dependence of ε′and ε″ have two kinds of power-law dependence in the frequency range of 5—106Hz due to the fractal structure in nanometer-sized amorphous films.The relationship between ε′and ωn－11 with n1=0.82—0.88- due to electron hopping are obtained at low frequency region,and the relationship between ε′ and- ωn－12 with n2=0.05 due to the fractal structure conduction are- obtained at high frequency region.