Abstract: The activity level of mobile sources in Altay City was obtained by top-down investigation, the emission factor method was used to establish the mobile source emission inventory, and the temporal and spatial characteristics of mobile source emissions and inventory uncertainty analysis were carried out. The results showed that the total emissions of pollutants from mobile sources in Altay City in 2021 were CO 669.12 t, NO_x 617.92 t, SO₂ 29.85 t, NH₃ 32.61 t, VOCs 136.35 t, PM_2.5 35.74 t, PM₁₀ 38.06 t, BC 20.33 t, OC 6.41 t, respectively. Among them, CO, SO₂, NH₃ and VOCs mainly came from passenger vehicles, contributing more than 40%; NO_x mainly from agricultural machinery and trucks, contributing more than 30%; PM_2.5, PM₁₀, BC, OC mainly from agricultural machinery, contributing more than 75%. The spatial-temporal distribution characteristics showed that the emission was the highest from June to August, and the emission in densely populated urban areas was relatively higher than that in other regions. The uncertainty of the emission inventory of 9 pollutants from mobile sources was −39.23%-56.27%, and the calculation results of this inventory were relatively reliable.