The present article is a research of Engaged Buddhism. Its basic nature will be studies according to the radical form of Engaged Buddhism. The article is composed of three sections. The first section is to discuss the Chinese translation of the term "Engaged Buddhism". I try to argue that the concept should primarily be understood in its French rather in English context, since in French cultural-social context "engage" has unique and significant implication that is lacked in its English counterpart. Based on various cases of Engaged Buddhism from South-East Asian, I argue that at least for radical form of "Engaged Buddhism", it is politically oriented. The second section is an analysis of four essential points of view in Engaged Buddhism, namely, (1) institutionalization of Ignorance (avidya); (2) De-cosmosologization of traditional Buddhist doctrine; (3) secularization of Buddhist community and its relation with the Civil Society; and finally (4) Engaged Buddhism's criticism on the modern form of substantialism----political and cultural nationalism. The third section is a further analysis of various problems relevant to the basic nature of Engaged Buddhism. Issues like (i) Whether radical form of Engaged Buddhism is a deviation of traditional Buddhism, which is claimed to be more spiritual oriented; (ii) Whether Buddhist practice should be related to political activity; (iii) Whether political resistance should be counted as one way of religious practice in Buddhist tradition; (iv) Engaged Buddhism's alienation, namely, the formation of Buddhist Nationalism...... etc will be included in the discussion of the last section