Abstract: Functionalized graphite oxide (MGO)/Poly(3-hydroxybutyrate) (PHB) nanocomposites with excellent thermal and mechanical properties were prepared via a facile solution intercalation method. The surfacial structure of MGO was characterized by using FTIR and AFM. The morphology, crystalline and mechanical properties of the MGO/PHB nanocomposites were investigated by using SEM, XRD, DSC and tensile test. The results indicated that the crystallization process was accelerated, leading to an increase in crystallinity. The surfacial interactions between MGO and PHB were improved effectively through chemical functionalization of MGO, leading to even dispersion of MGO in the PHB during solution blending. With the increase in MGO content, the flexural strength of MGO/PHB nanocomposites increased firstly, followed by decreasing. However, all MGO/PHB nanocomposites showed higher flexural modulus, compared with pure PHB. The variation of mechanical strength with the loading of MGO in the nanocomposites showed somewhat correlation with the threshold filler concentration.