A large number of archival microfilms are preserved in Chinese archives, libraries and other institutions. Vinegar syndrome is the most important reason that affects the life of archival microforms. In recent 30 years, archival microforms have been plagued by vinegar syndrome. How to monitor vinegar syndrome in time is a hot and difficult point in the research of visual archives protection. In this paper, the preservation status of archival microforms in Ethnic Library of China was investigated, and AD strips was used to monitor the occurrence and development of vinegar syndrome and its influence on archival microform. It is found that AD strips can accurately monitor the occurrence of vinegar syndrome, play a predictive and monitoring role in archival microform protection, and can better prevent and control vinegar syndrome.