Abstract: Repeatedly occurring sandstorms represent a significant concern in northern China because of their related hazards since particulate matter has harmful impacts on air quality in leeward cities. From March to April 2021, two sandstorms and one dust event (SDS) occurred in the Fenwei Plain. The spatial-temporal variation of aerosol chemical components was studied using simultaneous on-line ambient ions monitor, OC/EC online analyzer, weather and environmental data. The spatial distribution and transport of the sandstorms was represented by the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6.1 (C6.1) aerosol optical depth (AOD) product sand Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA 2) reanalysis datasets. Additionally, the ISORROPIA Ⅱ model was used to calculate aerosol water content and pH. The results showed that during sandstorm 1 (00:00, March 16^th-07:00, March 21^st), dust (08:00, March 21^st-14:00, March 28^th) and sandstorm 2 (15:00, March 28 ^th-21:00, March 31^st), the average PM₁₀ concentration in Xi´an City reached 309.5, 168.3 and 472.2 μg/m³, respectively, which was 2.7, 1.5 and 4.1 times higher than that before the sandstorm (00:00, March 10^th-22:00, March 15^th). The SDS events originated from Alxa League in Inner Mongolia and Jiuquan-Zhangye-Jinchang in Gansu Province, and experienced different transport pathways before reaching the Fenwei Plain, therefor the contribution of SDS to the surface PM_2.5 concentrations showed significant difference. PM_2.5 concentration increased by 2.5 times during sandstorm 2 compared with that before sandstorm, followed by the concentration increase in sandstorm 1 (1.2 times) and dust event (1.1 times). The content of water-soluble ions in PM_2.5 decreased during the SDS events, accounting for 45.8%, 37.9% and 14.8% of PM_2.5 in sandstorm 1, dust and sandstorm 2, respectively. Among the water-soluble ions, NO₃⁻ had the largest proportion in all SDS events, accounting for 24.6% (sandstorm 2)-38.7% (before sandstorm), followed by NH₄⁺, accounting for 19.1% (before sandstorm)-22.3% (sandstorm 2). The effect of the sandstorm process on the conversion of SO₂ to SO₄²⁻ was weaker than that of NO₂ to NO₃⁻. The proportion of POC (Primary Organic Carbon) in PM_2.5 was the highest in sandstorm 1, reaching 49.0%, and decreased to 42.3% and 41.2% in the dust and sandstorm 2, respectively, slightly lower than before the sandstorm. During sandstorm 1, dust and sandstorm 2, the water content of aerosols decreased by 29.9%, 43.7% and 6.2%, significantly, compared with those before sandstorm. The SDS process increased the concentration of water-soluble cations, resulting in an increase of aerosol alkalinity. The pH values of sandstorm 1 and sandstorm 2 were 6.7 and 6.5, respectively, which were higher than the pH (6.2) before the sandstorm. In summary, the impact of the SDS events on the PM_2.5 chemical composition in the Fenwei Plain was significant, leading to a significant decrease in aerosol water content, a increase in pH, a change in acidity/basicity, and even a change of the mechanism of aerosol chemical composition formation.