The natural ecosystems continue to face degradation and damage under human and natural disturbance. Thus, the societal demand for ecosystem restoration is rapidly increasing. Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. Restoration ecology is the field of science that studies the process of ecological restoration. As a young academic field, the conceptual framework of restoration ecology has been developed rapidly by integrating theory and practice over the past two decades. The present state of restoration ecology is still far away from Bradshaw's acid test for ecology."This review briefly introduces the theories and advances on restoration ecology. The major principles of restoration ecology, which are heavily based on contemporary ecology theories, include interaction among ecological factors, competition, niches, succession, recruitment limitation, facilitation, mutualisms, herbivory or predation, disturbance, genetic diversity, island biogeography, ecosystem function and biodiversity, plant-soil feedback, ecotypes, landscape heterogeneity, and scale, among others. The emerging theories from the practice of restoration ecology include the state and transition model, assembly rules, reference ecosystem, self-design and designerdesign, and adaptive restoration. Moreover, the review also reports the research advances and mainstream-recognition of restoration ecology from the perspectives of habitat, population, community, ecosystem, landscape, global change and anthropogenic disturbances. Restoration ecology has shifted from static, single state, structure-based, individual ecosystem to dynamic, multi-state, process-oriented, and landscape context. However, there are two major obstacles in the development of restoration ecology:(1)It still adopts simple experiments with few treatment factors and few levels of those factors, and(2)It focuses little on synthesis and has weak conceptual theory. Therefore, restoration ecology is facing two paradigm shifting: uniting the practice with the theories, and uniting science with arts(including social, economic, cultural, and political factors).