Abstract: Objective To evaluate the effect of polyfluoroalkyl substances (PFAAs) exposure on children's lung function,and to provide a reference for making effective measures to protect children's cardio-pulmonary function.Methods A total of 132 asthmatic children were selected from the affiliated hospital of National Taiwan University,and the other 168 non-asthmatic children were chosen from 7 public middle schools in Taipei.Multivariable and logistic regression models were used to examine the influence of PFAAs on lung function parameters and asthmaoutcomes.Results Children were prone to suffer from asthma with the increase of the concentration of PFAAS.And with the adjusted odds ratios (ORs) ranged from 1.32(95% CI--1.02-1.71) for the perfluorooctanesulfonate (PFOS) to 2.80 (95%CI=1.87-4.20) for perfluorooctanic acid (PFOA).When stratified by sex,more significant associations were found in males than in females.PFAAs and PFOA were negatively associated with lung function parameters (FVC,FEV1 and FEF25%-75%) among male asthmatics.For instance,if the levels of PFOS and PFOA increased by 1 μg/L in their serum,FEV1 may decrease by-0.062(95%CI=-0.0106--0.018) and-0.099 L(95%CI=-0.0197--0.001).Conclusion PFAA exposure can impair children's lung function,and and more significant associations were found in males than in females.