In recent years, developing students' knowledge integration of specific topics through effective teaching methods has been a concern in science education. This study explored an alternative teaching method, which aims to help lower secondary school students develop their knowledge structure about buoyancy towards a logically integrated conceptual framework through enhancing their understanding of the nature of buoyancy. Specifically, this study constructed a conceptual framework on buoyancy and a set of matching test questions to map out the three levels of knowledge integration of students, and designed and implemented a teaching experiment of promoting students' understanding of the nature of buoyancy. Through quantitative and qualitative analysis, it was found that the knowledge integration development of the treatment group was significantly better than that of the control group. The results indicated that enhancing students' understanding of the nature of buoyancy can effectively improve their knowledge integration of buoyancy. Accordingly, improving knowledge integration through enhancing students' understanding of the nature of the specific scientific concept may be a new direction for future research.