As a special phenomenon in the process of global warming, climate warming hiatus is characterized by slow, stagnated or decreased growth of air temperature. The ecology of the Mu Us Sandy Land is fragile and sensitive to climate change, the research on the hiatus and the characteristics of air temperature and precipitation has important referential value for the appropriate adjustment of regional vegetation ecology protection policies in this area. Based on the ground observation data of air temperature and precipitation in the Mu Us Sandy Land during 1970-2019, we adopted the linear trend method and the Mann-Kendall test method to analyze the hiatus and the characteristics of air temperature and precipitation in this area. The results showed the inter-annual and seasonal average air temperature and precipitation increased significantly (P<0.05), presenting the characteristics of “warm and humid” in the Mu Us Sandy Land during 1970-2019. From 1998 to 2012, the annual average air temperature change rate was -0.70 ℃/10a (P<0.05), hiatus was readily recognized. During the occurrence of hiatus, the average air temperature in each season showed a downward trend, with the highest decreasing rate in spring and winter; whereas the annual precipitation still showed an increasing trend, with the highest increasing rate in summer and autumn. After the hiatus (2012-2019), the change rates of the inter-annual and seasonal average air temperature reached 2-3 times of those of 1970-2019, and the annual precipitation showed a decreasing trend, with the highest decreasing rate in autumn and the highest increasing rate in spring. The inter-annual and seasonal air temperature and precipitation changes during and after the hiatus showed obvious opposite change processes. It is concluded that there was an obvious hiatus in the Mu Us Sandy Land during 1998-2012, which was characterized by a significant decrease in annual average air temperature and an increase in annual precipitation. Attention should be paid to the reverse changes of air temperature and precipitation during and after the occurrence of the hiatus, which may have a certain impact on the vegetation ecology change in the Mu Us Sandy Land.