Based on an ethnographic study on two cohorts of teachers and parents in China, this article reveals that social networking sites (SNS) have widened the channel for parents and teachers to establish and maintain a relationship, and has formed an online “community of practice” to promote such collaborations. Yet, this could be accomplished only at the expense of teachers’ professional and personal boundaries becoming increasingly blurred, which has emerged as a potential risk for their professionalism. Moreover, such a “community of practice” has also opened up a new space for winning or losing at the educational game for parents from different background, which has inadvertently led to widening the arena for the operation of old mechanisms of social inequality. This study suggests that further investigation should be conducted to examine the potential of SNS in the parent-teacher relationship.