Abstract: The nano Sb₂O₃/brominated epoxy resin-polypropylene (BEO-PP) flame retardance composite and the testing splines were obtained by ball milling dispersion and melt-mixing method, respectively. The mechanical properties and reinforced mechanism of the nano Sb₂O₃/BEO-PP composite were studied by XRD, DSC and tensile and impact test. The results show that the dispersion and the cohesive properties of nano Sb₂O₃ in the matrix are improved obviously by ball milling modification method; Meanwhile, nano Sb₂O₃ particles can enhance the toughness and strength of nano Sb₂O₃/BEO-PP composites. Besides, with increasing of the mass fraction of nano Sb₂O₃, the strength of the composites increases firstly and then decreases and the crystallinity of PP matrix also increases gradually. Nano Sb₂O₃/BEO-PP composites with 2wt% of the mass fraction of nano Sb₂O₃ possesses superior comprehensive performance.