Tsuji et al. investigated the crystallization behavior of poly L-lactic/poly D-lactic (PLLA/PDLA) blends with different ratios. The stereocomplex crystallite was observed using Differential Scanning Calorimeter (DSC) and Wide Angle X-ray Diffraction (WAXD). The melting temperature of stereocomplex crystallite is higher than that of PLLA homocrystallite. The presence of stereocomplex crystallite increases the total crystallization rate of PLLA/PDLA blend. Fujita et al. reported the blends of PLLA and PDLA homocrystallite exhibits the transition to stereocomplex crystallite during their lamellar thickening process. This peculiar phenomenon is hardly explained. Therefore, this study focused on the transformation of homocrystallite/stereocomplex crystallite of PLLA/PDLA (LD) blended filament, which were blended with the weight ratios of PLLA and PDLA in 50:50. The transformation of homocrystallite and stereocomplex crystallite was studied using WAXD, DSC, and Hot Stage Polarizing Microscope (HSPM). 　　WAXD analysis showed that there have no homocrystallite and stereocomplex crystallite can be observed in the L5D5 filament. DSC results showed that the endotherm of both of homocrystallite and stereocomplex crystallite can be observed in the filament. HSPM was therefore used to observe the transformation from homocrystallite to stereocomplex crystallite of the L5D5 filament during the heating process. The results showed that the stereocomplex crystallite was formed at 150 ℃ after the homocrystallite was melted. It means that the molecular chains were rearranged to form stereocomplex crystallite after the melted of the homocrystallite.