PBS was blended in a twin-screw extruder with unmodified nanoscale SiO2 and nanoscale SiO2 modified with KH570 to provide PBS/SiO2 nanocomposite. The heat resistance，mechanical properties and degradation of PBS/SiO2 nanocomposite were studied. The results showed that when PBS blended with nanoscale SiO2 modified with KH570 (m(coupling agent): m(nano-SiO2)=20%) by 4wt%, the vicat softening point of PBS/SiO2 nanocomposite increased by about 10℃, tensiles properties increased about 30%. Meanwhile, the degradation of PBS/SiO2 nanocomposite increased to certain degree than pure PBS.