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 fi...