Provided is a method of protecting archives with red-ink handwriting from spreading and sinking in during process of papering and repairing. The method comprises the steps of uniformly mixing, by mass, 1 part of phospho-tungstic acid, 2.3 to 3.9 parts of phosphoric acid, 48.8 to 52.0 parts of acetone and 2.8 to 9.2 parts of tetraeththyl orthosiliate to prepare a first reinforcing agent and coating the agent on red-ink handwritings; preparing a second reinforcing agent with 1 part by mass of ethyl cellulose, 6.25 parts by mass of barium hydroxide and 40 parts by mass of methanol and coating the agent on the red-ink handwritings coated with the first reinforcing agent; and preparing a third reinforcing agent with, by mass, 1 part of ethyl cellulose banana oil solution and 0.03 to 0.17 part of polymethylmethacrylate banana oil solution, wherein mass percentage of the ethyl cellulose banana oil solution is 4% and mass percentage of the polymethylmethacrylate banana oil solution is 4%, andcoating the third reinforcing agent on the red-ink handwritings coated with the second reinforcing agent. The method of protecting the red-ink handwritings enables improvement in tensile strength, folding strength and tearability of testing paper after dry heating aging, hydrothermal aging and ultraviolet aging tests. After the aging process, the handwritings which are reinforced by the reinforcing agents exhibit minor chromatic aberration. Pigments of the handwritings are not easy to fade and the handwritings can be durably kept.