Recently, it is becoming a research hotspot to improve photocatalytic activity of TiO2. The first row transition metal Cu and Cr are selected to be co-doped rutile TiO2. The effect micromechanism of electronic properties and optical properties of Cu-Cr co-doped rutile TiO2 are discussed by using the plane wave pseudopotential method based on the density functional theory. The results show that there are five new impurity levels formed in band gap of Cu-Cr co-doped TiO2. In which, one of impurity levels on valence band maximum is mainly contribution of 3d orbit of Cu, and another four metastable impurity levels are formed by interaction of 3d orbit of Cr and 2p orbit of O. Cu-Cr co-doped TiO2 is beneficial to decrease the transition energy of electron and largely improve photocatalytic activity of TiO2. The optical properties of Cu-Cr co-doped TiO2 is also improved, which has a red shift in visible region. And the reflectivity of TiO2 is increased. The visible light absorption ability and reflection ability of Cu-Cr co-doped TiO2 is more stable compared with these of Cu doped and Cr doped TiO2.