Security is the inverse function of risk, generally regarded as safeguard degree expectation state of assessment object or reliability of prevent imperfect and uncertainty event to happen. Ecological security can defined as mankind's ensure degree un-effected by ecological destroy and environmental pollution in yield, living and health, including basic element of water and food security, air quality and green environment. The mostly content of ecological security consists of ecological health diagnosis, regional ecological risk analysis, landscape security pattern, ecological security monitoring and prediction, and ecological security management and guarantee etc. Study on regional ecological security has characteristics of macro-scope and pertinence, assessment criterion of relativity and expansibility. Ecological security prediction and design should embody the capability of human activity. At last, authors discuss the measures of the ecological security ensure of inland watershed and ecological security analysis of oasis landscape.