Poly(lactic acid) (PLA), as an aliphatic polyester chemically synthesized from bio-derived monomers, is biocompatible and biodegradable. Different from other biodegradable polyesters, it is thermally stable which promises a great processability for industrial applications. However, its brittleness limits its usage. It is usually toughened with more ductile elastomer like polyurethane, rubber. In this study, natural rubber(NR) was added to toughen PLA and also clay platelets was mixed in order to improve mechanical properties. In this case, the blend composition of two polymers was widely expanded to obtain diverse morphology including bi-continuous structure. Bi-continuous morphology of the polymer blends is known to induce interpenetrating structure of two polymers, which is expected to bring unique properties compared to other morphology like droplet/matrix and fibrillar/matrix. Since polymers are usually immiscible with low interfacial adhesion, its system is often unstable. So several factors like nature of polymers (interfacial tension, viscosities, ratio of viscosities), their volume fraction, processing conditions must be in consideration. With a certain fixed composition of NR, different types of clay platelets were introduced with a small amount of weight fraction W_Clay, 0-7wt% to see their rheological and mechanical effect. With a small W_Clay, PLA/NR system showed different morphological change under FE-SEM images and this was reflected on rheological and mechanical properties.