Abstract: Blends of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) were melted and cut into slices in round shape. The rheological properties of the melt blends were investigated by means of advanced rheometric expansion system. Results showed that PLLA-PDLA melt blends were the typical kinds of pseudo plastic fluids and had high values of viscous flow activation energy with the apparent viscosity sensitive to the temperature. The apparent viscosity index of PLLA-PDLA melt blends decreased and the non-Newtonian index increased while the temperature increased. After different contents of nucleating agent TMP added into the melt blends, the non-Newtonian index decreased whereas the apparent viscosity index increased. The melt blends were suitable for spinning when m(TMP)/m(PLLA-PDLA) was 0.5%.