An e-retailer sponsored virtual community (ESVC), as the backyard of an e-commerce website, provides consumers with an online platform to play with each other. Different from transactional e-commerce platform, ESVC assembles consumers together to fulfil their social needs. In recent years, with the popular of Web 2.0 information and communication technologies (ICTs), e-retailers also start to integrate social media within ESVC. This greatly increases consumers' online community participation, as social media facilitate information sharing and interactions among community members with a social flavour. Moreover, social media provide a variety of IT artefacts to visualize the interactions between consumers and e-retailer, which reshapes the relationship between e-retailer and customer as a triad model. However, in this new context, the influences of ESVC characteristics and IT artefacts on e-retailer- customer relationship were not well investigated. Some researchers have made effort to open the "black box" between ESVC with social media investment and customer loyalty, but still lack theoretical foundations. This research explores the underlying mechanisms from a new perspective, and proposes a theoretical framework based on reciprocal theory.