Molecular composite materials made of various composite of nylon 6, PPTA and modified PPTA were prepared through sulfuric acid solution, and the mechanical and structural properties of the composite materials were investigated by some instrumental analyses such as UTM. SEM, XRD. RV, IR, HMR etc. from the result of these studies. we found the following facts. Firstly. it was found that the PPTA and M-PPTA were dispensed as a form of fibrils into nylon 6 matrix to make blentls of molecular composites. Secondly, mechanical properties such as initial modulus, yield stress and tensile strength of the composite materials were increased steadily according to increase of the composition ratio of PPTA alldyor M-PPTA.