High-speed melt spinning of sheath-core type bicomponent fibers was performed and the changes of fiber structure and property with increasing take-up velocity were investigated. The structure and property of bicomponent PET fibers spun in high-speed were analyzed through the density, birefringence, wide-angle X-ray diffraction, DSC, and stress-strain measurements. Two kinds of polymers, low molecular weight poly(ethylene terephthalate) (LMPET, η =0.62 dl/g) and high molecular weight poly(ethylene terephthalate) (HMPET, η =1.05 dl/g), were selected and spun in a sheath-core type at various take-up velocities of 1~5.5 km/min. In the structure formation of LMPET/HMPET bicomponent fibers caused by high-speed spinning, the molecular orientation of LMPET component was smaller than that of HMPET component. Orientation-induced crystallization of LMPET/HMPET bicomponent fibers in high-speed spinning was observed at take-up velocity about 4~5 km/min. As the spinning velocity increased, the amorphous orientation factor increased but the average loss tangent $delta$ decreased. In general, the LMPET/HMPET bicomponent fibers showed poor mechanical properties compared to that of LMPET single component fibers for high-speed spinning.