China has entered a period of large-scale bridge maintenance, and long-span cable-stayed bridges in service for more than 15 years are frequently facing issues such as water seepage at anchorages, excessive humidity, and corrosion of steel components. Via traditional sealing and monitoring methods, it is difficult to detect hidden hazards in concealed areas in a timely manner. In this paper, an anchorage end protection system that integrates visual monitoring and active humidity control while accounting for sealing conditions is proposed. Using actual cases such as the Jintang Bridge and Taoyaomen Bridge from the Zhoushan Island Link Project, the shortcomings of traditional maintenance measures and the causes of defects are analyzed. Experimental and onsite validation demonstrate that this system effectively delays corrosion, enhances detectability, and improves maintenance efficiency, providing an engineering reference for the full-lifecycle management of large-span cable-stayed bridges.