The capability of reading comprehension is one of the essential skills for learning different topics, and has been recognized as a challenging objective in the Chinese curriculum. In this study, a concept mapping-based summarization strategy was incorporated into flipped learning to improve students' reading comprehension. The participants of the study were 45 fifth graders from two Mandarin Chinese classes at an elementary school in Taiwan. None of the students had previous flipped learning experience. A pretest and posttest of reading comprehension as well as pre- and post-questionnaires for measuring the students' reading motivation, self-efficacy, and cognitive load were conducted. The experimental results show that the proposed approach improved the students' summarization skills, while the impact of the approach on students' reading comprehension was not significant. Moreover, reading comprehension and self-efficacy showed a positive correlation, and self-efficacy was positively correlated with both intrinsic and extrinsic motivation. Consequently, it is concluded that employing concept mapping with the summarization strategy in flipped learning and students' summarization ability are directly related, but there may be an indirect relationship with reading comprehension.