As Chinese NGOs are trying to go abroad under the Belt and Road Initiative, understanding the existing niche, discourse, and paradigm of the mainstream transnational NGOs in current international development aid system is crucial for Chinese NGOs to adapt and develop their own identity on value and norms. Based on key researchers' observations, historical facts and statistics, this research examines the mainstream NGOs' evolution in organization, action and discourse embedded in the macro-history of transnational NGOs and transformation of the international development aid system; it sums up the transformation around three macroscopic relations to understand and evaluate the action paradigm and discourse of the contemporary mainstream NGOs in transnational development, namely, around "Transnational NGO-State" relations a change from the private sphere to the public sphere, around "North-South" relations a shift from one-way aid to equal cooperation, and on "NGO-Society" relations an evolvement from voluntarism to professionalism. In the end the article points out the difference between Chinese NGOs and those of the developed countries in terms of the origin, timing, goal and discourse and specifies five basic questions China must face in its identity building. [ABSTRACT FROM AUTHOR]