Damages of ancient books due to repairing could be divided into three categories,i.e.,damages of the physical forms,damages of the textual contents, and losses of the physical components. Such damages mainly result from the violation of repairing principles, the misuse of repairing technologies and materials, over-repairing, repairers’ lack of professional abilities and knowledge, and the historical limitation of repairing technologies. To avoid such damages,more attention should be paid to the following five aspects. First,a national database of ancient book repairing archives should be established. Second, repairing plans should be made according to specific damages of ancient books. Third, principles of ancient book repairing should be fully understood and abode by. Fourth, appropriate repairing methods and materials should be chosen and used according to the specificities. Fifth,more importance should be attached to the role of philologists in the repairing of ancient books.