Abstract: This article explores how to optimize the multiobjective collaborative paths in the preservation of library collections, focusing on the instrumental value and application strategies of format conversion technologies. In the context of the intertwining of technological iteration and cultural demands, document preservation faces complex challenges and requires diversified solutions. This research systematically analyzes the characteristics of three types of reproduction formats: preservation facsimile, microfilm, and digital files, as well as the advantages, disadvantages and costeffectiveness of the associated conversion technologies. This research points out that when formulating document protection strategies, the preservation costs, risk factors, and cultural benefits of both originals and reproductions need to be comprehensively assessed, followed by selecting format conversion technologies based on specific needs while allocating resources judiciously to ensure secure storage and effective utilization of information. Additionally, it emphasizes the importance of avoiding overreliance on digitization and recognizing the riskbuffering role of microfilm technology to maintain a balanced technological ecosystem. Through a graded protection framework diagram and data analysis in nine tables, this article provides decisionmaking tools for the graded protection strategy of documents, emphasizing the achievement of an optimal balance between cultural heritage preservation and information dissemination through technological collaboration, aiming to simultaneously meet the needs of multiple objectives.