The nature viewpoint of Marx and Engels includes abundant and profound Eco-Philosophy: The nature of environment problems is people’s problems; The key of solving environment problems is to conquer gene onesideness; Science and technology are important means to solve environment problems; The relationship of people and nature is unification of the initiative nature and passive nature; Taking people as root is the most value of building an ecological civilization; etc. These thoughts are very important to insisting scientific outlook on development and implementing sustainable strategies.