The preparation and microwave—absorbing behavior of polyaniline—DBSA／montmori]lonite(PANI-DBSA／ MMT)nanocomposites were studied．The nanccomposite was synthesized by emulsion polymerization using dodecylbenzensulfonic acid(DBSA)as dopant and emulsifier．XRD

FT-IR and conductance measurements of the nanocomposite showed that the conductive emeraldine salt form of polyaniline was inserted into the layers of MMT to produce the nanocomposites with high conduetivity．The complex permittivity and permeability of a 2．00 mm thick specimen containing 50％ by weight of PANI—DBSA／MMT nanocomposite and PANI—DBSA were measured respectively in the range of 2～18 GHz

from which the reflection loss(RL)of microwaves was calculated and comparative absorption curves were given．The results shows that the PANI—DBSA／MMT nanocomposite is capable of absorbing 2．0—18 GHz microwaves

and the reflection loss is greater than -10 dB within the frequency range of 9．1—12．5 GHz．while the maximum reflection loss was-15．8 dB at 11 GHz．