Social trust that exists throughout the development of human society has close relations with human nature. Human beings need social trust in order to satisfy the psychological demand of their own security. To satisfy the psychological demand of security and to obtain sense of security are the basic agent to make social trust come into being. However, with the continuous development of society, human beings' psychological demand is also developing very fast. Human society needs social trust not only to satisfy the psychological demand of human beings' security, but also to satisfy the advanced psychological demand such as love, reverence and self-realization.To compare with the traditional society, modern society needs more social trust. Meanwhile, it is the most difficult thing to obtain social trust, or it is the easiest thing to lose social trust. More social trust is needed, especially in today's world that is being globalized day by day. Thus, there has been an upsurge of research on social trust in western social science world since 1970 and social trust has become a subject of western social science study. Now China is at its early transforming stage, and there are serious crises of social trust in such fields as economy, politics, society, etc. Social trust crisis indicates the serious lack of social trust. However, the development of socialist market economy needs higher social trust as its internal support. Thereupon, since 1990 Chinese sociologists have been doing research in social trust from deferent angles of their disciplines one after another. In a word, human beings need social trust, modern society needs social trust, the world of today needs social trust, and now Chinese society needs even more social trust. The continuous upsurge of research on social trust in western social science world is a theoretical response to western social trust study. The special research on the base of social trust is not only a theoretical response to western social trust study, but also a theoretical response to the need of social trust in China at present. Sociologists both in China and western countries who have carried on researches on the base of social trust from different angles of their disciplines have obtained many important achievements, such as theories of On Morality, On Political Institution, On Property Institution, Epistemology of Occurrence, Theory of Network Embeddedness, Theory of Rational Game, etc. on the base of social trust. However, their researches on the base of social trust have some deviations and flaws. One deviation is made in understanding social trust, expressed specifically in: (1) unilateral understanding of social trust. That is, the understanding of social trust is regarded as unilateral trust in others, such as Luhmann, Barber, Zucker, etc.; (2) simplistic understanding of social trust. That is, the understanding of social trust is regarded as universal trust in strangers, such as Weber, Smith, Redding, Fukuyama, etc.. The other deviation is made in the research on the base of social trust, expressed specifically in: (1) superficial explanation to the base of social trust. That is, the base of social trust is regarded as individual psychological experience, game relations among rational people, or interpersonal network relations as well as their embeddedness, such as Erikson, Coleman, Granovetter, etc.; (2) unilateral explanation to the base of social trust. That is, the base of social trust is regarded as cultural morality, political democratic institution, or property institution, such as Fukuyama, Seligson, Zhang Weiying, etc..Based on the critically inherited research made by Chinese and western sociologists on the social trust, the author will center on the core viewpoint that Institution is the base of social trust and make a complete and profound, general and concrete explanation from a new viewpoint of institution by using the internal and external institutions as new paradigm of institution research.Institut