The ring-opening polymerization (ROP) of O-carboxyanhydride (OCA) is the most powerful approach to produce diverse poly(alpha-hydroxyalkanoic acid) (PAHA) with functional groups as an easy modification of the side group of OCA. Previous studies focus on the ROP of OCA to produce linear PAHA, whereas no example was reported regarding the cyclic PAHA. Here, a synthesis strategy is reported for controlling the topology of stereoregular PAHA by the ROP of OCA. La[N(SiMe3)(2)](3) catalyst yields highly isotactic cyclic polymer, while Zn[N(SiMe3)(2)](2)/BnOH catalyst system favors highly isotactic linear ones. The individual enantiomerically pure cyclic or linear PAHA generates homocrystallites, which displayed distinct melting temperature (T-m) up to 190 degrees C. Mixing of these opposite enantiomerically pure cyclic or linear polymers in equivalent amounts affords the crystalline stereocomplexed PAHAs. This study provides a new approach to create crystalline polymers with controlled geometry, allowing a better understanding of the relationship between structure and properties to expand the potentials of their materials.