Abstract: Prefabricated construction is a significant direction for the industrialization of China's construction industry, rapidly developing due to its advantages such as environmental friendliness, energy efficiency, and short construction periods. However, during the construction of prefabricated concrete structures using aluminum alloy formwork systems, leakage issues frequently occur at the wall root and in the cast-in-place slab strip of composite floor slabs, seriously affecting the apparent quality and overall performance of the structure. Traditional mortar sealing methods are inefficient and ineffective, no longer meeting high-quality construction requirements. To address these issues, this study first systematically analyzes the causes of leakage, and then develops two reusable leakage prevention devices - natural rubber boards are used for sealing at the wall root combined with "L"-shaped vertical back ribs for reinforcement, and elastic rubber cushion blocks are used for the cast-in-place strip of composite slabs. Finally, construction process optimization and application verification are completed through engineering practice. The results of engineering practice show that this measure significantly improves construction quality, reducing leakage at the wall root by approximately 90% and the incidence of leakage in the cast-in-place strip by 85%. At the same time, construction efficiency is increased by 20% and construction costs are reduced by 15%. The research confirms that the developed reusable leakage prevention devices effectively solve the common leakage issues of traditional processes, combining the characteristics of convenient installation, stable sealing, and environmental friendliness. It provides a practical technical solution for addressing leakage issues in aluminum alloy formwork for prefabricated construction, and is of great significance for improving the construction quality of prefabricated concrete buildings and perfecting the technical system of prefabricated construction. It has broad engineering promotion value.