Abstract: The threshold of toxicological concern(TTC) is an approach for screening and risk assessment of chemicals when the chemical structure of the substance is known and where human exposure can be estimated to be relatively low. In cases where chemical-specific toxicity data are absent or limited, the TTC offers an alternative to assess human exposure below which there would be no appreciable risk to human health. The TTC approach is increasingly applied in many sectors such as food contact materials, food additives, pharmaceuticals and cosmetics. The development and application of the TTC approach are reviewed in this paper, with emphasis on the application and research progress of the TTC in the risk assessment of cosmetic ingredients. In addition, the particularity of the TTC application in the cosmetic field is discussed, so as to provide reference and ideas for the optimization and development of the TTC approach.