To further understand effects of titanium dioxide (TiO2) nanoparticles on thermal, optical, microstructural, interfacial and mechanical properties of shape memory polyurethane (SMPU), TiO2/SMPU nanocomposites with different TiO2 contents were synthesized. Then various properties of TiO2/SMPU nanocomposites were characterized. Results indicate that the melting temperature of soft segments in SMPU can be used as the shape memory transition temperature of TiO2/SMPU nanocomposites. TiO2 nanoparticles are almost filled in SMPU pores to form compact skeleton structures in TiO2/SMPU when the TiO2 content is 3% by weight. Further, the used TiO2 is rutile phase, and lowers the SMPU crystallinity. The suitable TiO2 content can increase the absorptivity to UV light and enhance the reflectivity to visible light of TiO2/SMPU nanocomposites, lowering its photo-aging properties and prolonging its service life. Also, TiO2/SMPU shows a higher scattering intensity and a faster decreasing trend than SMPU due to the larger electron density difference between TiO2 and SMPU. The microphase separation and ordered structures in SMPU are decreased due to added TiO2 nanoparticles. There are electron density fluctuations at the interfaces between hard and soft phases in SMPU, and between SMPU and TiO2 nanoparticles. Finally, the prpared TiO2/SMPU nanocomposites have better shape memory effects and tensile properties when TiO2 content of 3% is proposed to synthesize TiO2/SMPU nanocomposites for practical engineering applications.