XU Jing?zong was the Prime Minister and a historiographer in the Tang Taizong and Tang Gaozong periods of the Tang Dynasty. He directed and participated in the writing of various historical books in the Tang Dynasty, such as Guoshi (the national history), Shilu (the veritable records). His historical writings were usually disreputable and thought that they exaggerated the good and obscured the vice, falsified and tampered with the realities, and breached the professional moral principle that historians should record the history truly and factually. However, doubts have been raised recently by one scholar who attempts to exculpate him from the criticism above. This article argues that, whether from the history of the writing of Guoshi and the personality of XU Jing?zong or from the historical records, it is very difficult to deny the fact that he falsified the veritalbe records and Guoshi of the Tang Dynasty. The reason why it is noticeable that XU Jing?zong falsified the Shilu and Guoshi is closely connected with the political reality of the Tang Dynasty, particularly his relationship with Tang Gaozong.