Abstract: Nano-TiO2 reinforced polypropylene (PP) foam composite was prepared using supercritical fluid technique, and the influences of nano-TiO2 content on the foaming effect, flowability and mechanical properties of the foam composite were investigated by scanning electron microscopy (SEM) and standard tensile testing. Results show that nano-TiO2 could improve the foaming effect of the foam composite. When the content of TiO2 was 3wt%, the foaming effect was the best for the foam composite. The apparent viscosity decreased with the increase of nano-TiO2 content at 250 ℃. Nano-TiO2 could significantly improve the tensile and impact strength of the foam composite. When the mass fraction of TiO2 was 3%, the foam composite had the best tensile strength, impact strength and breaking elongation, which were 35 MPa, 19 kJ·m-2 and 289%, respectively.