A writer presents his/her skills of sensational description in a sheer aesthetic composition, while showing systematic thoughts in a practical one. The sensational description is the skin of literature, and the ornamentation is necessitated for pursuing sheer aesthetics. On the other hand, systematic thoughts are the soul of literature, and they cannot be expressed transparently without a writer’s erudition. Only an eminent writer can compose a both aesthetic and practical literature, for sheer art and thought are usually two opposite poles confronting in each work. However, Xu Ling can achieve both of them. He is not only a talent composer who can establish rules of aesthetics, but also a learned scholar who expresses his very thoughts with grounds and facts. Consequently, his compositions have a systematic structure and a tense content; it is decorated by skillful writing, thorough description and extensive citations. The following four rules of aesthetics Xu Ling established had become literature standards and writers' direction. First, the usage of rhyme and sound must be harmonious. Second, a parallel prose requires ornamented sentences and thorough description. Third, the lucid and natural connection of thoughts and illustration will bring a composition vividness. Last, the combination of poetry and prose is a genre that favorably presents profound thoughts. As to Xu Ling's actuality, is presented on his devotional and honest writing. When he was restrained in a foreign country as a minister, he expresses his anger and lonely in letters. After Xu Ling came back his country in the south, the compositions present a loyal official's strategy on politics. Xu Ling's literature acquires both aesthetics and practice, and it becomes not only a tool of expression, but also a paragon for writers.