Abstract: Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic aliphatic compounds, which are found widely in environmental media and are potentially and persistently hazardous to human health and the environment, thus being considered as persistent organic pollutants (POPs). Numerous experimental and population - based epidemiological studies have shown that exposure to PFASs not only causes various toxicities in the body, but also leads to changes in thyroid hormone (TH) level and increases the risk of hypothyroidism, which in turn causes various clinical symptoms such as developmental delays and metabolic disorders. In this paper, we describe the toxicokinetic processes of PFASs in humans, based on several long - chain, short - chain and emerging PFASs, and summarize effects and possible mechanisms of PFASs exposure on thyroid function.