中文摘要：

中共中央水利工作会议的召开再次凸显流域生态治理对经济社会可持续发展的重大意义，然流域生态治理至今仍是公共治理理论研究的难题。流域生态治理问题究其根源及矛盾冲突所在，缘于流域生态的外部效应及其公共物品特征引致的个体选择与集体目标的背离。在技术分析层面上，集体的大小以及集体中个体数量的多寡对于个体行动选择尤其是搭便车行为有显著的影响。小集体治理方式比大集体行动更具效率，既可增加个体一致行动的承诺，也可更好地贯彻有效监督原则，是提高治理效率的有效途径。考虑流域生态涉及多元利益相关主体复杂的相互依存关系，结合个体行为选择的技术分析。多元小集体共同治理模式将是解决现有流域生态治理困境的有益尝试。

英文摘要：

The CPC Central Committee conference of irrigation highlighted the significance of fiver valley＇ s ecological management in a sustainable way, which is still a difficulty in public governance. The basic reason of the conflict comes from the inconsistent of the collective purpose and the individual selection, which was affected by the external effects. By analyzing the size of collective and the number of individuals affecting the personal selection, we know that governance by small-collective, which would increase the individual consistency of action and implement supervision of principles effectively, is more effective than governance by a large group. So small-collective governance is an effective way to improve the efficiency of fiver valley＇ s ecological governance.