This paper investigated the ecological reason of unbalanced, inharmonious and unsustainable problems existed in China's fast social-economic development, and summarized the theoretical and methodological progress in Social-Economic-Natural Complex Ecosystem Study after its emergence 30 years ago. The paper explained the concept and approach of ecological integrity, and the scientific foundation, system approach and integrative technology for incorporating ecological civilization into all aspects and the whole process of advancing economic, political, cultural, and social progress. The study also pointed out that the target of ecological research is transformed from components to contexts, from material to information, from structure to function and from academic interests to social wellbeing; and the approach is transformed from quantity measurement to functional order measurement, from optimization to adaptation. Moderately prosperous society,ecological harmonization, and great scientific wisdom are the objectives of China's ecological civilization by 2020.