Trust is a concept involving multiple dimensions including psychology, society, economy and culture. This paper summarizes the main viewpoints of the major psychologists and sociologists on trust. When the society changes, the connotation and function of trust will change accordingly. According to Georg Simmel, in the transformation from the traditional society to a modern one, the main type of trust changed from personality trust to institutional trust; Niklas Luhmann divides trust into interpersonal trust and institutional trust and Barber, B. sees trust as an expectation of technical competence and credit responsibility. Fukuyama stresses that irrational choices were an important force for economic prosperity, but that culture was more important than institution.