According to the data of temperature in "haiyuan city from 1916 to 2000，using periodic method，the temperature varanon in 'haiyuan city during recent 85 years is studied.  "hhc results show that the mean annual temperature and the mean temperature in winter of "haiyuan city appear to be ascending,  the mean temperature in spring,  summer and autumn appear to be descending. It was discovered that there was the period of 13 and 17 years in the mean annual temperature, and the period of 17，l} and }5 years in spring, the period of }8 and 15 years in summer, the period of }8，}2，18 and 13 years in autumn, and the period of }3，17 and 13 years in winter, In recent 85 years，the annual and seasonal mean temperature experienced three stages of high一low一high，and by the end of 20th century, the mean temperature in each season was ascending.