The work aims to modify PBT with multilayer graphene to improve its heat resistance and mechanical property. PBT/multilayer graphene (MLGN) nanocomposites were prepared by melt blending method. The effects of multilayer graphene on the properties of PBT were studied by the tests of DSC, SEM, DMA, heat resistance and mechanical properties. MLGN had obvious het-erogeneous nucleation effect, which significantly reduced the crystallization activation energy of PBT by 66.2% after adding 1% MLGN and by 72.8% after adding 2%. MLGN and PBT had strong interaction between the molecular chains, which was conducive to the improvement of peak temperature of crystallization, glass transition temperature, Vicat softening temperature and tensile strength. When the mass fraction of MLGN was 2%, the glass transition temperature increased by 1.7 ℃, the Vicat softening temperature increased by 8.8 ℃ and the tensile strength increased by about 17%. There was no influence on impact strength when the mass fraction of MLGN was within 2%. MLGN can significantly improve the heat resistance and mechanical properties of PBT.