Abstract: Na-bentonite from purified and modified Ca-bentonite was modified with organic hexadecyl trimethyl ammonium chloride（CTAC）.Influences of dosage of CTAC，reaction temperature，and reaction time on organic degree were discussed and optimal experiment conditions were as follows: the dosage of CTAC was 35%（mass fraction） of Na-bentonite， reaction temperature was 70 ℃，and reaction time was 2 h.The best sample was characterized by IR and XRD.Results showed that the CTAC cations were successfully absorbed in the layers of bentonite clay and the layers′ distance was obviously expanded，and the modification effect was well.

Key words: bentonite, CTAC, organized modification, structure characterization