China has had and will continue to have population opportunity window over a long period of time, but only under certain conditions it could be converted into demographic dividend. Compared to the increasing population quantity, it will be more effective and sustainable for China’s economic growth by improving population quality, developing human resources at all ages and participating into the global economy. The belief that China could only sustain its development by maintaining a large and cheap labor force and therefore China’s birth rate should be increased is a misunderstanding of the serious population situation in China and is detrimental to China’s economic structure transition. Adjusting population policy is essential for building a harmonious society, but it has nothing to do with the demographic dividend.