Abstract: Based on the daily average temperature and daily minimum temperature observation data of Baotou Meteorological Station during the ice flood season from 1959 to 2020, the temperature change and cold air characteristics of different intensities at the Inner Mongolia reach of Yellow River during the ice flood season and La Nina event were studied by statistical analysis, linear trend estimation and Mann-Kendall test. The results show that the annual average frequency of cold air affecting the Inner Mongolia reach from 1959 to 2020 is 36.5 times. The frequency of weak cold air accounted for 59.1% of the total frequency of cold air, and there was a significant positive correlation between the frequency of weak cold air and the temperature of Baotou station during the ice flood season (α=0.05). There is no significant negative correlation between the frequency of strong cold air and the temperature of Baotou station during the ice flood season. In the years affected by La Nina events, the temperature in ice flood season is mainly low. During the year of La Nina developing, the cold air of Baotou station was less in general from November to December, especially the strong cold air, which was less by 44% and 29%, respectively. From January to February, the frequency of strong cold air and cold wave is generally higher with especially in February being 16% and 13% higher, respectively. During the year of La Nina sustaining, the frequency of strong cold air and cold wave in January is 19% and 82% more than that of the multi-year average respectively. During the year of La Nina declining, the frequency of moderate and weak cold air in November is more than that of the normal year, while the frequency of strong cold air and cold wave is less by 33% and 52% respectively than that of the normal year.