Currently in the world, ancient manuscripts are considered rare documents, a heritage of historical memories of mankind. Therefore, preservation and restoration play an important role in the preservation of the above heritage. Preservative preservation activities help preserve document integrity and recover almost the original state of the document before it is damaged. In libraries where the manuscripts are kept, they always pay special attention to the preservation and restoration of these rare documents and the preservation is also done very carefully, carefully and systematically. The paper discusses the preservation and restoration of handwritten documents at the Library of Congress and the Library of Japan - two of the world's largest libraries that have documents in general and handwritten documents in particular are very effective, thereby giving some implications for Vietnam in the preservation of documents at libraries.