Among numerous emperors in Chinese dynasties, there was no one as well quoted and retrospected by later dynasties as Tang Taizong. Once this image of wise monarch was established in later Tang dynasty, the legend was transmitted constantly from one dynasty to another. We can say that there were a kind of aspect, so to speak, ‘Tang Taizong phenomenon’ in political history of China. Most of Chinese monarch who had a political ambition had shown interest in Tang Taizong, and this was not different in the case of so-called dynasties of conquest. Although criticisms for moral defect was raised to him, many emperors of each Chinese dynasty tried to learn from and imitate Tang Taizong. ‘Tang Taizong phenomenon’ is a interesting topic itself and seems to be an important subject to understand the trait of Chinese political history, but has not seen it’s related studies yet. This essay is dealing with the evaluations and criticisms mostly made by each dynasty’s emperors of China including from later Tang era to Ching dynasty.