Air pollution is easy to induce all kinds of respiratory diseases, causing serious damage to human health. In this study, the health effects of air pollution on respiratory system in Xigu District of Lanzhou from 2014 to 2018 were investigated by using the time series generalized additive model (GAM) of Poisson regression and the analysis method of population stratification. The results showed that:(1) Air pollutants such as PM_2.5, PM₁₀, SO₂, NO₂, O₃8h and CO had a lag effect on the occurrence of respiratory diseases. For every 10 μg/m³ increasing in pollutant concentration (1 mg/m³ increasing in CO), the increasing of hospitalization for respiratory diseases were 1.06%, 1.04%, 1.10%, 1.07%, 0.97% and 3.83%, respectively, in the best lag days. Gaseous pollutants (SO₂ and NO₂) were more harmful to human respiratory system than particulate matter (PM_2.5 and PM₁₀). (2) PM_2.5, PM₁₀, SO₂ and NO₂ had the greatest impact on pneumonia, and the harm to women's health was slightly higher than that of men. O₃8h had the greatest impact on chronic obstructive pulmonary disease, and the impact on men's disease was slightly higher than that of women. Asthma, upper respiratory tract infection and bronchitis were significantly affected by SO₂. (3) People aged 0-14 years were the most susceptible group of respiratory diseases, followed by those aged ≥ 65 years. (4) Winter and spring were the high incidence period of respiratory diseases. The concentration of pollutants and the number of hospitalized patients with respiratory diseases in a single day in the heating period were higher than those in the non-heating period, and the lag period of respiratory diseases in the heating period was about 2-6 days earlier than that in the non-heating period. (5) In the multi pollutant model, the interaction of different pollutants had synergistic or antagonistic effects on respiratory diseases. Among them, PM_2.5, PM₁₀ and CO were independent risk factors for the increasing in the number of hospitalized residents with respiratory diseases in Xigu District, and SO₂ exposure had the most significant influence on the results of different stratification.