Completely exfoliated epoxy/clay nanocomposites with comprehensive high performance were successfully prepared using Nano-disassembling method. In this method, nano-SiO2 was added into the montmorillonite and epoxy mixture system as disassembler to interact with montmorillonite (MMT). By means of the strong interaction between nanoscale particles, the MMT layers were completely disassembled into elemental nanometric mono-platelets. These mono-platelets took interlacing arrangement with the disassembler particles in the resultant nanocomposites. Mechanical testing and thermal analysis results indicated that the epoxy/MMT nanocomposites prepared by the Nano-disassembling method displayed dramatic improvements in multiple properties over conventional epoxy/organo-MMT nanocomposites. At the optimal MMT content of 5 phr, tensile modulus and tensile strength increased by 64.2 and 52.3%, respectively. Flexural modulus enhanced by 7.1%, flexural strength by 14.6% and notch impact strength by 37.7%. Glass transition temperature and thermal decomposition temperature moved to higher temperatures by 10.1 and 5.7 degrees C, respectively.