Discolored teeth will have a negative impact on the beauty of the face. As a conservative technology to improve tooth color, cold light whitening is widely used in clinical practice, which can improve the color of physiological yellow teeth, dental fluorosis and tetracycline teeth. Based on the mechanism of discolored teeth and the effectiveness and safety of cold light whitening, this paper reviews the therapeutic effect of this technique and its influence on dental pulp, soft tissue and hard tissue, in order to provide some reference for the rational use of this technique in clinic.