Abstract: An investigation of the effect of nano-material on the mechanical properties of nano-nylon fiber was carried out,and a comparative study between the nano-nylon,photo-electronic nylon and ordinary nylon was made in terms of the strength,elongation rate,breaking energy,initial modulus,relaxation and elastic recovery.The experiments showed that in compared with the ordinary nylon,the nano-nylon has lower strength,elongation rate,and breaking energy but higher initial modulus and elastic recovery.They have similar curves of relaxation of stress.The sun light has little influence on nano-nylon’s breaking strength and elongation rate while its initial modulus has been impacted greatly.In respect to the relaxation velocity,the sunlight has greater influence on nano-nylon than on the ordinary nylon.