Abstract: The vermiculite concentrate is organic modified with hexadecyl trimethyl ammonium bromide (HDTMAB) and vermiculite and organovermiculite are characterized by X-ray diffraction spectrometry (XRD), infrared spectrometry (IR), differential scanning calorimetry （DSC） and gravitational thermal analysis (TG). The experimental results show that when the mass ratio of vermiculite to water is 1∶10 in reaction suspension and the reaction temperature is controlled at 60~70℃, HDTMA cations enter the interlayer gap of most vermiculite particle and enlarge the distance between the crystal layers of vermiculite (the distance of the (001) crystal plane of vermiculite increasing from 1.45986 nm to 3.70134 nm). HDTMA cations enter the gap between single crystal particles of vermiculite and separate the vermiculite particles into single crystal particles with nanometer size.