Along with industrial development, adverse impacts on the natural environment become more serious, and the states of ecosystem health and ecological security have also deteriorated. As the basic needs for human survival,ecosystem health and ecological security possess very important meanings. Therefore; ecosystem health and ecological security have become research hot topics in recent decades. This paper reviewed the developments of definitions and applications of ecosystem health and ecological security, and found that the research on ecosystem health had achieved a lot. However, the research on ecological security was still relatively undeveloped. Moreover, there are also some confusion between the concepts of ecosystem health and ecological security. We consider that ecosystem health indicates the status of the ecosystem in normal conditions, whereas, ecological security indicates the capabilities of an ecosystem to react to extal accidents or extremely adverse effects. An ecosystem which is healthy does not mean that it is secure.However, the ecological security requires an ecosystem to possess the capacity for integrity against any risk, and ecosystem health is the precondition to ecological security.