Abstract: In order to quantify the contribution of cloud water and rain wash-out below the clouds to SO₄^2- and NO₃^- in wet precipitation and further to differentiate the contribution of scavenging SO₄^2- and NO₃^- in particulates and of scavenging SO₂ and NO₂ in the air below the clouds to SO₄^2- and NO₃^- in wet precipitation, the segmented wet precipitation were collected by APS-3A precipitation automatic samplers from April 2016 to February 2017. The ρ(SO₄^2-) and ρ(NO₃^-) in segmented wet precipitation were detected by ion chromatography and then the variations were analyzed. SO₄^2- and NO₃^- in particulates and SO₂ and NO₂ in the air before rainfall, during rainfall and after rainfall were synchronously monitored. Then we analyzed variation of ρ(SO₄^2-) and ρ(NO₃^-) in particulates and ρ(SO₂) and ρ(NO₂) in the air before rainfall, during rainfall and after rainfall. The results showed:(1) During the same wet precipitation process, the ρ(SO₄^2-) and ρ(NO₃^-) in segmented precipitation decreased gradually and tended to be steady in the final stage of wet precipitation, which illustrated that the wet precipitation scoured the atmospheric pollutants and kept the air clean gradually and that scour effect of the rain became limited, leading to stable of ρ(SO₄^2-) and ρ(NO₃^-) in later wet precipitation period. (2) The mass concentrations of SO₄^2- and NO₃^- in particles, and the mass concentrations of SO₂ and NO₂ in the air were the highest before rain; they decreased during rain, and increased after rain, illustrating that the wet precipitation could scavenge SO₄^2- and NO₃^- in particulates and SO₂ and NO₂ in the air; but the concentrations of those pollutants increased slightly without the effects of rain wash-out after rain. (3) The contributions to SO₄^2- and NO₃^- in wet precipitation ranged from 22% to 56%, with an average of 35%, and from 9% to 49%, with an average of 29%. The contributions to SO₄^2- and NO₃^- in wet precipitation of SO₄^2- and NO₃^- in particulates scavenged below the clouds ranged from 39% to 69%, with an average of 55%, and from 43% to 73%, with an average of 56%. The contributions to SO₄^2- and NO₃^- in wet precipitation of SO₂ and NO₂ in the air scavenged below the clouds ranged from 5% to 17%, with an average of 10%, and from 5% to 19%, with an average of 15%, respectively. These results indicated that SO₄^2- and NO₃^- in wet precipitation were mainly from cloud water and SO₄^2- and NO₃^- in particulates scavenged below the clouds, and minor from SO₂ and NO₂ in the air scavenged below the clouds.