Based on the radiosonde data of Dunhuang, Jiuquan, Zhangye and Minqin stations from 2014 to 2019, the characteristics of cloud vertical structure in the northern Qilian Mountains are analyzed. The results show that the occurrence frequency of clouds in the northern Qilian Mountains is 20% to 40% in the whole year, and the occurrence frequency of singlelayer clouds is higher than that of multilayer clouds, which are mainly 2layer clouds; the occurrence frequency of clouds is higher in summer and lower in winter, the frequencies of singlelayer and 2layer clouds in summer are close, and the occurrence frequency of singlelayer clouds is much higher than those of 2layer clouds and 3layer clouds in spring, autumn and winter; the thickness of the lower layer clouds of 2layer clouds is obviously greater than that of the upper layer clouds, and the thickness of the clear air interlayer between the bottom layer and the middle layer of the 3layer clouds is greater than that between the middle layer and the top layer; cloud heights in the northern Qilian Mountains change significantly in different seasons, higher in summer and lower in winter.