In the investigation,the melt blending of polybutylene succinate ( PBS) and a novel plasticizer epoxidizedsoybean oil ( ESO) was carried out by using an internal mixer,and a series of PBS /ESO blends were thusprepared.Moreover,the effects of the ESO content on the mechanical and rheological properties of PBS /ESOblends as well as on their morphologies were discussed.The results show that ( 1) the introduction of the ESO significantlyimproves the tensile and impact toughness of the PBS; ( 2) with the increase of the ESO content,theelongation-at-break and the impact strength of the PBS /ESO blends first increase and then decrease,and at the ESOcontent of 5%,they both reach the maximums which are respectively 15.0 and 1,4 times those of PBS; ( 3) thetensile strength,tensile modulus,flexural strength,and flexural modulus of the PBS /ESO blends decrease with theincrease of the ESO content; ( 4) the addition of ESO significantly decrease the complex viscosity of the moltenPBS,thus resulting in an earlier shear-thinning transition of PBS; and ( 5) the PBS /ESO blend with a higher ESOcontent exhibits a distinct phase separation,which indicates that the ESO/PBS blend is a partially miscible system.