Maximum and minimum temperature can be used as a key indicator or index for climate change or the intensity of an extreme climatic event.By using the observational temperature gradient data at the heights of 1,2,4,10,16 m obtained in the Dingxi Arid Meteorological and Environment Experimental Base from 17 October 2003 to 6 April 2004,the characteristics of maximum and minimum temperature changes were analyzed.The results show that daily maximum temperature decreased from lower layer to upper layer,while the minimum temperature increased,which accords with the law of exponent/logarithm.The maximum temperature appeared(2.5) hours after the noon,and if there was a severe weather event,the maximum mostly appeared after 20:00.The minimum temperature appeared first at the height of 2 m,and mostly appeared before sunrise at the heights lower than 4 m while appeared after sunrise at the heights higher than 4 m.