Analysing the products of ozone-treated aflatoxin B1 (AFB1) is essential in order to study the practical use of ozone treatment. In this paper, the products of AFB1 were investigated using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC Q-TOF MS). The products were well separated using UPLC, and the accurate masses of all the products were determined using Q-TOF MS. Finally, the possible pathways of fragmentation ion generation from the products of AFB1 and the structures of four products were proposed. From the view of the proposed structures of products, the C8-C9 double bond in the terminal furan ring was destroyed. According to the structure-activity relationship, the toxicity of products was significantly reduced compared with that of AFB1. The result indicated that ozone was an effective agent for degrading AFB1, and UPLC Q-TOF MS was a useful analytical tool for proposing and identifying a series of unknown products.