The copolymer of styrene-ethylene-butylene-styrene triblock copolymer-g-polylactic acid (SEBS-g-PLA) was successfully prepared using a novel solvothermal synthetic method, in which the graft copolymerization of PLA and SEBS was simply performed in cholorform solution at 100-150 degrees C with benzoyl peroxide (BPO) as initiator. The effect of various factors including the reaction temperature and time and the content of BPO and PLA on the graft copolymerization was investigated in detail. It is found that the optimal reaction condition for the grafted copolymers SEBS-g-PLA was 120 degrees C for 5 h, while the optimal formulation of SEBS/PLA/BPO was 5 g/2 g/0.5 g in 30 mL chloroform. The properties and microstructures of the obtained SEBS-g-PLA copolymers were also studied. The tensile strength and elongation at break were higher than that of pure SEBS and improved with the increase of grafting degree. In addition, SEBS-g-PLA copolymer possessed two-phase structure with vague phase boundaries. The as-prepared SEBS-g-PLA copolymers can be used as the toughening component to improve the impact strength of PLA. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2699-2706, 2011