Abstract: Among nearly 600 poems written by LI Shangyin, the great poet in the late Tang Dynasty, there are many descriptions of “night” image and abundant expressions of “night”. Statistically, more than 550 words and expressions are used to depict night image in LI Shangyin's poems, which indicates that he is quite skilled at descripting night image in his poems. The night image in LI Shangyin's poems can be roughly summarized into the images of moon, lamp, dusk, dream, etc. These images are used to show the aesthetic features of coldness, loneliness, mournfulness, and sentimentality, which are caused by social and personal factors relatively of the spirit changes in the late Tang Dynasty, and Li Shangyin's family changes, and his characters.