By reexamining the process of China's modernization centered on its population in the past half century, this paper explores the grim situation of China's population, historical factors, the relationship between population, resources and environment. Also, focused on controlling the size and improving the quality of China's population, this paper discusses how China's population policy coordinates with the sustainable development strategy. Based on statistics and preliminary data released by the Chinese government and international organizations, this paper analyzes specific problems and implication found under the framework of Western modernization theory, and concludes that China faces a dilemma on population problem and the sustainable development of society: China cannot improve its socioeconomic status and retain growth in population. Both the lower quality and higher quantity of China's population are the major causes of the vicious cycle of "huge increase in population -- shortage of resources -- environmental degradation".