In order to explore the law of soil freeze-thaw in Hexi Corridor

based on the hourly surface temperature data of ERA5-LAND

the changes of surface soil freeze-thaw state in the past 40 years were analyzed by dividing different freeze-thaw stages and combining Mann-Kendall trend test and linear regression method. The results showed that: (1) The number of occurrence days in the spring transition period were more in plains than in mountainous areas

and the average annual occurrence days were more than 65 days. The number of occurrence days of complete melting period was more in the north than in the south

more in the east than in the west at the same latitude

and the number of occurrence days in more than 200 days was increasing. The number of average annual occurrence days in the autumn transition period was the least

about 50 days

and the number of days of complete freezing increased with the increase of altitude

among which the spatial distribution of the number of days in the spring transition period changed significantly with time. (2) The start date of the spring transition period and the complete melting period was gradually postponed from north to south

and the maximum difference between the north and the south was more than 90 days

and the spatial distribution of the start date of the complete melting period in different periods changed significantly. The start date of the autumn transition period was the opposite of the former

gradually advancing from north to south

and there was no obvious difference in spatial distribution between different periods. Most areas were completely frozen in December

and high-altitude mountainous areas were fully frozen in November. (3) The start date of the spring transition period was lagging behind in most areas of the study area

and the start date of the complete melting period was advanced

so the number of days of the spring transition period decreased at a rate of 0.2 d/a

while the start date of the autumn transition period in most areas was lagging

resulting in the increase of the number of days of complete melting period at a rate of 0.3 d/a. The number of days of complete freezing period in the northern part of the study area increased

while the southern Qilian Mountains showed a decreasing trend

and the start date of the complete freezing period was generally delayed at a rate of 0.03 d/a. (4) The number of days of complete melting in mountainous areas

oases and desert areas in the past 40 years increased at the rates of 0.393

0.321 and 0.288 d/a

the start date was advanced by 0.134

0.188 and 0.206 d/a

the number of days of complete freezing period decreased by 0.353

0.219

and 0.016 d/a

respectively

and the start date was delayed at the rate of 0.06

0.1

0.01 d/a. Under the trend of global warming

for every 1°C increase in annual average temperature

the number of days of complete melting increased by 8.1 days

the start date was advanced by 4.53 days

the number of days of complete freezing period decreased by 9.02 days

and the start date was delayed by 3.27 days. The results can provide a theoretical basis for the study of soil freeze-thaw response to climate change.