With the emergence of a large number of newly unearthed documents，the study of Tang Dynasty literature has also made progress. Especially through the comparison of newly unearthed documents and handed-down documents, traditional epigraphy has further developed in the modern academic context. However, the discovery of new documents does not mean a complete subversion of previous studies or even historical conclusions. Its value lies in making use of the rich information provided by epitaphs and inscriptions to supplement and perfect the historical details. We should also keep a calm and objective attitude towards the utilization of unearthed documents. This paper starts from the perspective of literary research and employs close reading as the main method to analyze the differences between unearthed documents and documents which have been passed (over time), and identify the causes of textual fissures.  The newly unearthed ″Yang Zhiyi's Tombstone″ has an extremely high literary value. This stele was written by Zhang Yue, a famous chancellor of Tang Xuanzong. After comparing it with the ″Epigraph of Yang Zhiyi″ by He Zhizhang, we can find that there are three obvious differences in the historical narrative. Yang Zhiyi once participated in the Shenlong coup as a Qianjishi, helped Emperor Zhongzong to return, and alsohelped to put down a border rebellion during the time of Emperor Xuanzong, an achievement for which he is still known today. In Zhang Yue's narration, Yang has been a good military general throughout his life, but in He Zhizhang's narration, Yang Zhiyi, who was deeply influenced by his family studies, was an elegant and polite scholar-official. Secondly, in order to avoid the censure of political opponents, Zhang Yue omitted the reason why Yang Zhiyi was demoted and driven away from Xuzhou. But in He Zhizhang's narration, Yang Zhiyi was relegated because he offended Zhang Jiazhen, the counterpart and political rival of Zhang Yue. Finally, Zhang Yue, as a good friend of Yang Zhiyi, criticizes Yang's ″overcorrection″ when he governed Shuofang. He Zhizhang, however, wrote the words ″Zhongkou Shuojin″ and ″Baiyu Chenglin″ because of sympathy for Yang Zhiyi. The background of this narrative variation is the preparation of the grand ceremony of Fengshan led by Zhang Yue. Zhang Yue and He Zhizhang, as colleagues at Jixiandian academy, adopted different narrative strategies in dealing with the life stories of Yang Zhiyi. In He Zhizhang's narration, Yang Zhiyi learns etiquette and literature from his childhood. Zhang Yue's ″military general″ stories do not contain such descriptions. He Zhizhang's words in defense for Yang Zhiyi after Yang had been wronged reflect the factor of personal emotions. The conflict between the two documents reflects the tension between the orthodox narrative and individual cognition. The innovation of this paper lies in the fact that, by analyzing the similarities and differences of stele biography, epitaph and historical biography, it shows the author's public-private approach by shifting between the writers, politicians, historians. At the same time, it reveals how the differences between the stele and epitaph, as different literature carriers, demonstrated in stylistic requirements, material forms, implied readers and other aspects, might lead to the variation of historical narrative. At present, academics pay more and more attention to the role of newly unearthed documents. Only by placing the research object in the context of multiple texts, distinguishing between the internal norms and pursuits of different styles, in order to open up the space of literary value of historical documents, will more research value emerge than the pure historical facts.