Based on the whole chain of recycled polyethylene terephthalate（recycled PET，rPET），potential migrants in recycled flakes，pellets，preforms and bottles/migrants in the food simulation solution were untargeted screened by ultrahigh performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry（UPLC－Q－TOF MS）．Thirty kinds of intentionally or non-intentionally added substances including PET oligomers，lubricants and rinsing agents were screened out．MS－DIAL（Mass spectrometry－data independent analysis software） was employed to screen the markers of rPET products in different production stages．The results showed that new PET oligomers were formed during the processing from pellet to preform．Alcohol ethoxylate was detected in the flakes of rPET due to the clean process．Comparing the relative content of PET oligomers，it was found that the relative content of cyclic oligomers in rPET was higher than that of linear oligomers，while the relative content of the second series of cyclic dimers was the highest．The relative content of several kinds of oligomers and lubricants increased during rPET processing．Finally，the TEST（Toxicity estimation software tool） was used to predict the rat oral acute toxicity，developmental toxicity and Ames mutagenicity of potential migrants/migrants．And the classification of potential migrants/migrants by Cramer rules was performed by Toxtree software. It was found that PET cyclic oligomers and amide lubricants were all classified as Cramer Ⅲ，which was more toxic than linear oligomers，suggesting that attention should be paid during the rPET recycling process．