Abstract: Using conventional observation,FNL 1° × 1°and NECP 0.25° × 0.25° for 4 times one day reanalysis data and other data to explore the causes and predictability of extreme low-temperature rain and snow weather in the northern plain of Bayingolin Mongolian Autonomous Prefecture（Bazhou for short） from May 2nd to 7th,2023. The results showed that:（1） extreme low-temperature rain and snow weather occurred in the upper northern hemisphere with an eccentric polar vortex. In the circulation background of 500 hPa Ural Mountain blocking high pressure development and long-term maintenance of deep Central Asian low vortices in Xinjiang,the impact of low vortex duration and cold center intensity on the southern slope of Tianshan Mountain was rare in May;（2）the strong cold air crossed the western Tianshan Mountains from the northwest path and entered the southern Xinjiang basin. It merged with the cold air from the eastern part of the southern Xinjiang basin and strengthened in the northern part of Bazhou. The precipitation area was located in the center of the low-level warm advection and the 850 hPa frontogenesis area,and the change from rain to snow exacerbated the decrease in the minimum temperature in the northern plain of Bazhou;（3） the EC model had poor predictability for the Central Asian low vortex when predicting the situation 96 hours in advance,and could accurately depict the strength,position,and movement path of the low vortex within 72 hours,but there were deviations in the details;the EC model for predicting minimum temperature was stable,accurate,and had strong reference value;the intelligent grid and NCEP,EC,and CMA-GFS numerical models had limited predictive capabilities for precipitation and snow phase prediction in the urban area of Korla.