Abstract: In order to explore the impact of meteorological conditions on the severe dust pollution in Ningxia, conventional meteorological observation data, NCEP reanalysis data and ambient air quality data are used. Two severe dust pollution events from the January 11^th to 14^th, 2021 and March 14^th to 19^th, 2021 (referred to as ‘0113’ and ‘0315’ processes respectively) are selected as the research objects. Based on the methods of weather situation, backward trajectory simulation and physical quantity field diagnosis, the effects of the two processes on the system and transmission trajectory are compared, and the formation and maintenance mechanism are discussed. The results show that: (1) The ‘0113’ process mainly affected the 4 cities in northern Ningxia, and the ‘0315’ process affected the entire region of Ningxia. The average duration of severe pollution or above is 35.0 hours and 105.2 hours, respectively. The average PM₁₀ concentration of the dust pollution ‘outbreak’ stage is 1735 μg/m³ and 5265 μg/m³, respectively. (2) The ‘0113’ process is a severe dust pollution weather caused by the passing of the front of average intensity. A significant pressure gradient band is formed between the stable and low-moving Qinghai-Tibet high pressure and the Mongolia thermal low pressure to the north. Several strong northwest air currents in front of the upper ridge decreased the momentum, and the wind transported dust to Ningxia and the upstream area, causing severe pollution. The ‘0315’ process is a relatively strong and typical front transit and continuous severe dust pollution process caused by the Mongolian cyclone. The Mongolian cold high pressure is stable and less moved by the strong Mongolian cyclone and the Tibetan Plateau thermal low pressure. A pressure gradient band with two thermal low pressures is formed in its southwest, southeast and east. In addition, affected by the transit of the surface cold front, the multi-direction winds in Ningxia and the surrounding areas transported dust over Ningxia, resulting in heavier pollution in the ‘0315’ process than in the ‘0113’ process. (3) Both processes transported dust from overseas and inside China at the same time, the ‘0113’ process transported dust from northwest and west with long transmission distance and low altitude, and the ‘0315’ process transported dust from northwest, north and east paths, with short transmission distances and high altitudes. (4) The central value of the negative horizontal helicity in Mongolia and Xinjiang-Gansu region of China during the ‘0315’ process is 1.75 times that of the ‘0113’ process. The relatively strong convergence upward movement and westerly air flow continue to transport dust to Ningxia and overlap with local dust. The alternating upward and downward movements keep dust suspended in the air for a long time. However, the ‘0113’ process is caused by a number of strong downdrafts that rapidly settle to the ground, and the pollution rapidly weakens. The research shows that the cold fronts and Mongolian cyclones are the main influencing systems of severe sand and dust pollution weather in Ningxia. When the cold front passes through, the upstream sand and dust transport height is low, and relatively few sand and dust particles reach Ningxia, making the duration and intensity of severe sand and dust pollution weather in Ningxia short and relatively weak. When accompanied by Mongolian cyclone activity, the sand and dust transport height is high, and more sand and dust particles reach Ningxia, resulting in long-lasting, wide-ranging, and high-intensity sandstorm pollution weather in Ningxia.