In order to improve the mechanical properties of PET fiber, the conventional spinning technique was innovated by heating spinline with electric tube heater. The spinline heater was fifed at the position of 20 cm from the nozzle. The length of the heater was 15 cm and the temperature in the center of the tube heater was 25$0^{circ}C$. Fine structure characteristics and mechanical properties of the PET filaments, which were obtained by 5 steps of take-up speeds(3,000~7,000 m/min), were experimented and discussed. Mechanical properties of the obtained PET filaments were increased with the spinning speed below 5,000 m/min, but decreased very rapidly at the spinning speed 7,000 m/min. Especially using of spinline heater, the properties were not decreased evenly above the 5,000 m/min, because molecular orientation of amorphous region was improved., but that of Na-g-Nylon 6 was remarkably increased. The fiictional electrostatic charge of Na-g-Nylon 6 fiber with increasing grafting yield was developed little. The changes of mechanical properties of fabrics, bending rigidity(B), hysteresis of bending moment(2HB), shear stiffness(G), and hysteresis of shear force at 5$^{circ}$ of share angle were increased, which indicated much increase of KOSHI and HARI value and decrease of SHINAYAKASA.