Poly(L-lactic acid) (PLLA) filament fibers prepared by one-step melt spinning process with spin drawing were annealed at $100^{circ}C$ and $120^{circ}C$ and the effects of annealing on the crystal structure, crystallinity, and orientation of PLLA were studied by using synchrotron wide angle X-ray diffraction (WAXD) method. The PLLA SDY fibers of this study showed an ${alpha}$-form crystal structure which was not affected by the annealing. The crystallity, crystallite size of the (200) plane of ${alpha}$-form crystal, total orientation (${Delta}n$), and crystalline orientation ($f_c$) increased with increasing annealing time up to 30 minutes at 100 and $120^{circ}C$.