The preparation experiment for organic intercalation and polyamide 6/montmorillonite nano-composite was carried out by using six kinds of montmorillonites with different causes of formation,mineral types and properties as raw materials. The influence of different types, compositions and cation exchange capacity (CEC) of montmorillonite on the organic intercalation and exfoliation was studied. Results show that the basal spacing of organic intercalated montmorillonite is increased with increasing amount of organic molecule used and the CEC of montmorillonite. However montmorillonites with low CEC and high Na~+ content are favorable to its exfoliation. Na~+ exchanged montmorillonite seems to have little influence on the organic intercalation.