The effect of architecture of polymer chain on the crystallization of PLLA was studied. Especially, the effects on the crystallization of α and α’ crystal structures and morphology of PLLA were investigated. PLLA will form an tightly packed α form crystal structure at higher crystallization temperature and an loosely α’ form crystal structure at lower crystallization temperature. However, α and α’ can co-exist at moderate crystallization temperatue. When star-shaped PLLA is added, it is difficult to form stable nuclei and requires longer crystallization time due to the core unit which is considered as impurity and is excluded from lamellae. Two factors affect the crystallization of α and α’ in varying degree, resulting in the coexistence temperature change. The α and α’ coexistence temperature is much lower for star-shaped PLLA system. In order to further understand the effect, different composition of linear and star PLLA blends are studied. Also, the morpholgy and crystallization kinetics are investigated.