Objective To study the reaction kinetics characteristics of tenuazonic acid (TeA) and tentoxin (TEN) in water during chlorination, identify the structure of chlorine disinfection by-products(DBPs), and preliminarily explore the cytotoxicity of disinfection by-products. Methods The disinfection reaction process of TeA and TEN was simulated in the laboratory, and their reaction kinetic characteristics were further investigated. The reaction products were identified by ultra-high performance liquid chromatography tandem time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and nuclear magnetic resonance spectrum, and the toxicity of TeA and its disinfection by-products were evaluated by toxicity prediction and cytotoxicity. Results TeA produced two kinds of DBPs (DBP-188 and DBP-240) in simulated chlorine disinfection reaction, while the chlorination reaction of TEN was slow, and no DBPs were found. Reaction kinetic studies indicated that the reaction rate of TEN with chlorine increased with increasing chlorine concentration and pH in the reaction system. In vitro toxicity prediction analysis found that the oral toxicity, developmental toxicity and carcinogenicity of the DBPs of TeA were higher than the maternal toxicity. Conclusion Alternaria toxins produced disinfection by-products after chlorination. The reaction process was influenced by the concentration of chlorine and pH.Cellular experiments showed that the DBPs of TeA had some cytotoxicity.