With the increasing attention to the role of parents in children's learning, what issues parents consider and how they behave when learning with their children when confronted with the emerging augmented reality (AR) technology may be worth exploring. This study was therefore conducted to qualitatively understand parents' conceptions of AR learning and approaches to learning by AR with their children. A total of 90 pairs of parents and children were invited to participate in an AR book reading activity held in 2015; all of the parents were then interviewed to acquire the research data. Through the phenomenographic method, this study generated several categories of the parents' conceptions of and approaches to AR learning. Further analysis identified the relationships between parents' conceptions and approaches. For example, the parents holding cohesive conceptions (e.g., learning by AR as attaining in-depth understanding) tended to use deep approaches (e.g., offering guidance to connect life experiences with the book content for thorough reading). Based on the findings, a framework of interactive AR book systems for child-parent shared reading is proposed. This study was expected to initiate research in the area of learning by AR in informal learning environments.