||This study is a case study concerning about the anti-dam movement on Nu Jiang, a large river in Southwestern China. By demonstrating detailed and complicated interaction process among environmental NGOs (ENGOs), the fragmented state institutions and the external forces of international organizations, the author find that it is the appropriate political opportunity contributed overwhelmingly to the temporary suspension of dam construction on Nu Jiang. The four aspects of the political opportunity are the openness of Chinese state, the availability of elite allies, including informal political elite allies and formal international and media allies, the division among Chinese political elite institutions, and the capacity of state repression. As an integrated composition of this political opportunity, international connection of local NGOs plays key roles. On one side, it supply political protection for involving NGOs, on the other side, international linkage may bring about negative impact for domestic NGOs. From my investigation, the degree and measurement of repression that state institutions put on ENGOs varied, it depends on whether the ENGOs hindering the hydropower group to pursue economic interest. The protection from higher level officials in the State Environmental Protection Administration played critical roles in the complex game among political actors in the anti-dam campaign. Chinese state still control civic organizations via co-optation measurements, in this regard, the political opportunity that has been grasped by ENGOs in this case is embedded into the controlling system. Nonetheless, the interaction between divided political elite and civic environmental organizations may potentially cultivate a legal space of civil society in contemporary China.