In the contemporary society, it is important to cultivate students' visual literacy. However, there has been a lack of sufficient training for students to improve their visual literacy in the classroom. A problem-posing approach (Visual Thinking Strategy, VTS, a learning strategy with question sequences to facilitate critical inquiry) has been proposed to achieve this objective. However, problem-posing should be supported with scaffolds to help learning deeply. And concept mapping is such a scaffold to aid problem-posing in visual literacy cultivation. In this study, a quasi-experiment was conducted on two classes of undergraduate students in Shanghai to evaluate the effects of the proposed approach. An online learning system was developed based on the proposed approach; moreover, a quasi-experiment was conducted on two classes of undergraduate students to evaluate the effects of the proposed approach. The experimental results show that the concept mapping-based online problem-posing approach improved the depth of students' visual analysis, which indicates sharpening of students' visual literacy and their critical thinking tendency. The interview results further showed that the students perceived the approach as being effective from the perspectives of "increasing visual analysis capability," "developing thinking capability," and "improving self-reflection in learning."