Abstract: Synthesis and mechanical properties of epoxy/clay nanocomposites are studied in this paper. It is found that the affinity between the organoclay and epoxy resin is very good and the organoclay is easy to be intercalated by epoxy resin with or without solvent. By direct or solution mixing, a stable and homogeneous epoxy/clay intercalated hybrid can be obtained in which the basal spacing of clay increases to about 3.7nm. Using two different kinds of organoclay, both exfoliated and intercalated epoxy/clay nanocomposites are achieved. In the former case, the clay exfoliates completely and there is no trace of X-ray diffraction peaks while in the latter case the clay retains its previous structure and strong X-ray diffraction peaks remain. Mechanical properties test results show that the exfoliated nanocomposite performs better than the intercalated nanocomposite of the same compound. But even in the exfoliated nanocomposites the mechanical properties of epoxy resin are not improved magnificently as in the cases of thermal plastic.