The bentonite was modified using Ca-bentonite as a matrix and octadecyl/ hexadecyl ammoniumsized by dispersing it into the dimethyl benzene-methyl alcohol system fully.The optimum process conditions for organic modification were that the coating agent dosage is 22g/L, reaction time is 90 minutes and the pH value of pulp is 10.X-ray diffraction ( XRD ) analysis indicates that the d (001) value of the modified bentonite is 20.532A.The influence of gel temperature on its viscosity characteristic was studied.By analyzing the transmssion electron microscopy (TEM) images and observing the dispersed gel, the nanometer effect of the organic gel was discussed.