The invention belongs to the technical field of document preservation, and relates to a paper document quality-keeping processing method. After processed by six steps of preparation of an insect-resist agent, preparation of quality keeping pulp, preparation of quality keeping liquid, preprocessing of documents, preparation of a quality keeping liquid film of a document, and storage of the document with film sealing, the paper document can be effectively prevented from deterioration, damages, writing fading and insect erosion, so that the paper document as well as paper calligraphy and painting can be stored with quality kept for a long time, and particularly, writings on the document can be prevented from fading or adhering to one another. The operation steps are simple and feasible, a paper document quality-keeping processing device is simple in principle and reasonable in structure, the processing process is reliable, the quality-keeping processing method is application environment friendly, the use effect is good, and the quality keeping period of the processed paper document is long.