The crystallization behaviors and morphology of PLLA with a few amount of PDLA (<10%) were studied. Besides the homo-crystallization of PLLA, PDLA and PLLA polymer chains can co-crystalliz together with 1:1 ratio to form a stereocomplex crystal (SC). The effect of SC on the crystallization behaviors and morphology of PLLA were investigated utilizing DSC, POM, and XRD . Interesting, the melting point of SC is about 50 oC higher than that of PLLA homo-crystal. Therefore, the SC was formed before the crystallization of PLLA. From the results of POM and XRD, it was found that the PLLA homo-crystals were able to be formed in three different sides: “inside of SC spherulite”, “front edge of SC spherulite”, and “between SC spherultes”. The crystallization behaviors in these sides were different. The induction time for the nucleation of PLLA in the side, “between SC spehrulites”, was the longest among three sides. They were about the same in other sides, “inside of SC spherulite” and “front edge of SC spherulite”. Obviously, SC acted as a nucleating agent and accelerated the nucleating of PLLA crystals. However, the growth rates of spherulite for three sides were about the same and slower than that of neat PLLA. Obviously, the amorphous of PLDA acted as impurity and reduced the growth rate of PLLA spherulites. Growth rate was not influenced by SC