The work aims to review the current research progress of oligomers in PET packaging materials, including identification, migration detection, risk assessment, policies and regulations. Identification of oligomers in PET packaging materials was mainly conducted by liquid chromatography coupled to high resolution mass spectrometry (HRMS) with both targeted and non-targeted screening procedures. Migration detection of oligomers was carried out by measuring the amount of oligomers migrating from PET packaging materials to food simulants under different conditions. Detection of oligomers in real foods was also conducted, while appropriate sample pretreatment methods were applied. Risk assessment of oligomers was mainly performed by comparing the concentration of oligomers in food/food simulants with the corresponding migration limits either listed in policies and regulations or obtained via a threshold of toxicological concern (TTC) approach with implementation of Cramer classification scheme. By far, due to the lack of experimental data, policies and regulations on oligomers in PET are scarce. With the expanding application of PET in packaging, especially the commercialization of novel PET materials, it is quite necessary to fully investigate the potential risks of oligomers in PET to ensure food safety. It is believed that HRMS plays an important role in exploring oligomers in PET and their migration behaviors, which in turn could provide essential data for future risk assessment.