Taboo is an ancient custom in China. The taboo system was applied to the names of emperors had a long history in China. Beginning from Zhou Dynasty, until to Qing Dynasty. It is true that taboo system has caused confusion of the recording of ancient Chinese books and inconvenience to the study of historical materials, but one will be able to apply its principle to appraise the authenticity of those books and materials of one has a good grasp of it. Taboo studies also have a long history. According to Chen Yuan’s陳垣 Shi hui ju li史諱舉例，there are different ways to avoid the forbidden words, such as change the character, blank character, omit a stroke, change the pronunciation, etc. This paper claimed that besides change the forbidden word to a synonym, other ways to achieve taboos were occurred in Han Dynasty, such as “missing one stroke of a Chinese character”, “change the formation of a Chinese character”, “change the shape of a Chinese character”, etc. That means the old conclusion of Chen Yuan and other scholars may be not true. However, philologists argued that those changes are the result of the variant form of a Chinese character異體字. Scholars stated that the way to avoid a tabooed word in Han dynasty was to change the forbidden word to a synonym. In this paper, according to Louji’s 婁機 Hanliziyuan漢隸字源, Hongkuo’s洪适 Lishi隸釋, Zhou Guangye’s周廣業 Jing shi bi ming hui kao經史避名彙考, we examine the relationship between tabooed character and variant form of a Chinese character. Finally, discuss the importance of variant form of a Chinese character in the aspect of taboo studies.

Taboo character is typical phenomenon of Chinese characters system, it is considered as the effective key in decrypting the date of Han-Nom texts inscirption texts. Such key is maintained clearly on the ancient books add steles of Vietnam, specially Taboo characters system in the insription texts of Tran Dynasty (1225-1400). Based on research results, we have found a new form of Taboo character previously published in studies in Vietnam Taboo characters. Such new characters forms have helped us easily discover in cription texts at the date of Tran dynasty in Ninh Binh. This is the useful and reliable source for researching of Vietnam Taboo characters in particular and ancient books of Vietnam in general.