Background The respiratory system changes with age and a better understanding of the changes contribute to detect and prevent respiratory dysfunctions in old population.The purpose of this study was to observe age-associated changes of pulmonary function parameters in healthy young adults and the elderly.Methods A cross-sectional study was conducted among 600 male and female subjects aged 19 to 92 years.The subjects were divided into three groups by age:young adult (19-39 years),middle-aged adult (40-59 years),and the elderly (≥60 years).The pulmonary function was measured with routine examination methods and 13 parameters including vital capacity (VC),residual volume (RV),functional residual capacity (FRC),total lung capacity (TLC),RV/TLC,forced vital capacity (FVC),forced expiratory volume in one second (FEV1),FEV1/FVC,peak expiratory flow (PEF),forced expiratory flow at 25％ of FVC exhaled (FEF25),forced expiratory flow at 50％ of FVC exhaled (FEF50),diffusion capacity of the lung for carbon monoxide (DLCO),and specific diffusion capacity of CO (KCO) were collected and analyzed.Changes in pulmonary function parameters among the pre-elderly and elderly subjects,especially the aging influence on FEV1/FVC and RV were studied further.Results Ten pulmonary function parameters including VC,FVC,FEV1,FEV1/FVC,PEF,FEF25,FEF50,TLC,DLCO and KCO decreased significantly with age in both male and female subjects (P ＜0.01).RV and RV/TLC were increased with age (P ＜0.01).FRC remained stable during aging.Except FRC,the linear relationship was significant between age and other pulmonary function parameters.In the pre-elderly and elderly subjects,RV had a non-significantly increasing tendency with age (P ＞0.05),and FEV1/FVC did not change significantly with age (P ＞0.05).Conclusion Total pulmonary function was declined with advancing age,but FRC was stable,and the increasing tendency of RV and decreasing tendency of FEV1/FVC obviously slowed down in the pre-elderly and elderly subjects.