Abstract: A type of bio-degradable thermoplastic composites was prepared by melt blending PLA and PBS with the nano-SiO2 particles encapsulated with microcrystalline cellulose (MCC). The effect of nanoSiO2 on the mechanical property, thermal stability and crystallinity of the composites was investigated by SEM, TGA, DSC and DMA. The experimental results indicated that the encapsulation of nano-SiO2 with MCC enhanced the dispersion of nano-SiO2 particles in the matrix due to an improvement in interfacial compatibility between the matrix resins and fillers by MCC. Compared to the PLA/PBS/MCC compounds containing 5 % MCC, the PLA/PBS/nano-SiO2-MCC composite with 5 % MCC exhibited an increase in storage modulus, impact strength and crystallinity degree by 13.04 %, 11.70 % and 71.92 %, respectively.