The toxicity of traditional Chinese medicines is one of the basic properties of traditional Chinese medical pharmacology theory. Chinese medical doctors have a long history of understanding the toxicity of traditional Chinese medicines, and have adopted the methods of compatibility and processing to achieve synergistic and toxicity-attenuating effects. This article summarized several aspects including the properties and toxicity of traditional Chinese medicines, the processing methods and functions, current researches on the toxicity-attenuation by processing of traditional Chinese medicines, and the prospects on toxicity and processing of traditional Chinese medicines. The toxicity of traditional Chinese medicines should be treated correctly, and rationally recognized and used in both basic research and clinical application.