With the development of internet, some online social communities have been founded, most people, in such online social communities, have good relationships with the other people, they believe in each other and share a lot of business experience. Relational marketing, based on online social marketing, becomes an important marketing channel. In this paper, relationship quality is defined as the mediate variable, the correlation between marketing channel, and relationship marketing are examined by empirical analysis. The results show that, improvements of interaction frequency between sellers and buyers , as well as special knowledge of sellers, can advance relationship quality between sellers and buyers, then enhance customer loyalty indirectly. In addition, the stronger customer feeling is, the better relationship quality will be. Once suppliers own good relationship quality with their customers, they will keep the marketing channels for ever.