Abstract: The fracture behavior and tensile strength of the epoxy composite (Bisphenal-A type epoxide E-51) filled by Al₂O₃, CaF₂ and glass bead were investigated.The relationship between the tensile strength and volume fraction of filler was examined.It was found that the dense boundary layer with a certain thickness onto the surface of the filler would form when the filler was embeded in the epoxy matrix.The strength behavior of such an boundary layer has an important contribution to that of the composite.The tensile strength of three filled composites was measured.