In this study, we try to apply the transaction cost theory to explore the relationship among the trust, transaction cost and loyalty of online consumers. In order to find these correlation above, we collected online and common questionnaires from experienced online consumers and processed the data using regression analysis. There are total 161 valid questionnaires. It shows: (1) the trust of consumer has negative influence on transaction cost (2) transaction cost doesn't has negative influence on loyalty, (3) A test of an alternative moderating perspective shows that the effects of online consumers on loyalty is positive moderated by transaction cost. Loyalty is positive influence indirectly by increased trust.