Fibers of high density polyethylene having melt flow rate of 11 and 28 (g/10 min) were produced by high-speed melt spinning method in the range of take-up velocity from 1 to 8 km/min. The change of fiber structure and physical properties with increasing take-up velocity was investigated through the birefringence, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), Rheovibron, and Fafegraph-M. The birefringence increased with sigmoidal shape according to increasing take-up velocity, and that of HDPE(11) was higher than HDPE(28). With increasing take-up velocity, the crystal orientation of HDPE transformed a-axis orientation into c-axis orientation. In dynamic viscoelastic behavior of HDPE fibers by the high speed spinning, the intensity of crystalline relaxation peak was decreased and crystalline relaxation temperature shifted to lower. Tensile strength and initial modulus were increased and elongation was decreased with increasing take-up velocity. HDPE(11) fibers was preferred to HDPE(28) in mechanical properties because of increment of crystal and amorphous orientation factors. The change of birefringence with take-up veloicity was closely related to both initial modulus and tenacity uniformly.