Abstract:The theoretical framework of sustainable development may be traced back to the philosophical prime of ancient civilizations and it contains the summary of the practical activities in modern society: The sustainable development based on scientific value can only be realized when Human’s extortion from nature must equal his compensation on nature;Human’s efforts for the contemporary world must equal his efforts for its posterity;People’s exertion on their local region must equal their endeavor for other regions.At the same time,sustainability science fully reflects the human practice in various social activities,epitomizing a perfect integration in the relationship between "humanity and nature" and the inter-dependence between "man and man".It contains the duality of the two keynotes: the balance between "humanity and nature" and the harmony between man and humanity.Starting from this point,we are to explore the rational laws governing human behavior,the coordinated evolution between humanity and nature,the space-and-time coupling of the development itinerary,self-disciplined degree in human demands,the norms of integrate benefits and widely endorsed ethical code in human behavior.Through equilibrium,self-adjustment,optimization,coordination,eventually,the co-existence between humanity and nature and social justice among people may be reached.In this paper,the author summarized the following sustainability theories: the 3-D explanation of sustainable development in the nature,economy,and society field;the critical threshold towards sustainability development;the mathematical models of sustainability;the capacity building formula of sustainability;the calculation of green GDP under sustainability;and practice and actions of China’s sustainable development strategy.