|An improved Hummers method was used to prepare graphene oxide (GO). Then, the orthogonal experiment design methods were used to select the optimum conditions of preparation for graphene oxide-polymethyl methacrylate (GO-PMMA) via activators regenerated by electron transfer for atom transfer radical polymerization (AGET-ATRP). The optimum preparation conditions were determined by orthogonal tests. Furthermore, poly(lactic acid) (PLA)/GO-PMMA nanocomposites were prepared by melt blending to improve the comprehensive performance of PLA. Analysis results indicated that methyl methacrylate (MMA) was successfully grafted onto GO, and the addition of 0.3 wt% of GO-PMMA increased the tensile strength, elongation at break, and impact strength of PLA/GO-PMMA nanocomposites by 7.82, 40.66, and 50.62%, respectively, compared with PLA. Moreover, GO-PMMA eliminated the cold crystallization of PLA matrix and improved the crystallinity of PLA by 27.55%. In all, this study provided an effective and feasible method for improving the comprehensive performance of PLA.