Abstract: Nano ZrO₂  was first modified with the poly(ethylene terephalate) prepolymer via polycondensation to increase its compatibility with PC. The nano ZrO₂ /PC composite was successfully prepared by blending extrusion. The modified nano ZrO₂ particles were characterized by FTIR，XPS，TEM，TG and contact angle test. The results show that the PET can be successfully combined to the surface of nano ZrO₂ by the chemical bond， the hydrophobic property is improved and a good dispersibility is obtained. The mechanical performance of nano ZrO₂ /PC composite was tested，  and the relationship with the content of nano ZrO₂ was discussed. The results show that the mechanical performance of nano ZrO₂ /PC composite is better than that of pure PC. The notch impact strength and the tensile strength of the composite first increase and then decrease with the addition of the nano ZrO₂，and they reach the maximum respectively when the mass fraction of the nano ZrO₂ is 1% and 0.3%. The flexural  stress of the composite is increased in the experimental range，and the maximum is 2.54 MPa higher than that of pure PC.