As a promising photocatalysis material, TiO₂ has long been studied by experimental and theoretical methods. The external strain could affect the catalytic reactivity of TiO₂ significantly due to the difference in surface elastic properties of different surface structures with different surface adsorption or defects. This article reviews our recent work by using density function theory calculations on the effect of strain on the TiO₂ surface properties, including surface relative stability, surface defects, surface adsorption and dissociation.