Based on the principle of harmony between man and nature, “optimal disaster” emphasizes the initiative to adapt to nature, to adapt to the environment hazard, then，through transforming local environment, reduce or even avoid disaster losses, achieve the goal of lucky risk-averse. Engineering disaster prevention measure transforms nature, and “optimal disaster” conforms with the nature, avoids the hazard perception of environment. It is a effective path to realize the harmonious of ecological environment system,and sustainable development.