The 21st Century is the time for human seeking harmonizing with environment and carrying out sustainable development strategy. But sustainable development is facing many challenges. They may mainly include the follows: challenge comes from the contradiction between human and the earth, challenge of local benefit conflict to human common goal, challenge of competition to fairness, challenge of unbalanced development in regions and countries, challenge of diversity and challenge of calamity. Challenges are not only pressure, but also the motive force. Challenge exists, the motive force would never stop. Sustainable development was born in challenges, is developing in contradiction and will sustain in conflict.