In this work, the adsorption and photodegradation of acetaldehyde and ethylene on TiO2 nanoparticles (NPs) with dominant {001} facets were studied. Additionally, the first principle calculation was used to complement the experimental results. TiO2 NPs were synthesized by using a hydrothermal method. The experimental results indicated that adsorption amount of acetaldehyde on TiO2 {001} facets is higher than ethylene, with the initial concentration as 50010ppm. Photodegradation efficiency of 88% was achieved for acetaldehyde in contrast to 17% for ethylene at flow rate of 10sccm. The first principle calculations show that the adsorption energy (E-ads) for acetaldehyde is 0.603eV and that of ethylene is 0.251eV. This study is imperative for understanding the adsorption and photodegradation process of acetaldehyde and ethylene, two typical VOCs, and helpful to design the photocatalysts with high efficiency. [GRAPHICS] .