The present invention discloses a method for producing a clay/AMO complex by modifying layered inorganic silicate clay with the intercalating agent AMO (amine-terminated Mannich oligomer). The AMO is prepared by polymerizing polyoxyalkylene amine having molecular weight over 1000, p-cresol and formaldehyde. The present invention also discloses a method for producing nanosilicate plates by extracting the AMO from the above complex with a hydroxide or a chloride of alkali metal or alkaline-earth metal. The extracted AMO can be recycled for reusing.