The invention discloses a formula, a preparation method and application of a pencil board softener. According to the formula, the pencil board softener contains an emulsifier, a penetrant, a softener, a lignin removal agent, a degreasant, a protective agent and water, and all the components are proportioned in a certain mass ratio. The preparation method comprises the steps: weighting all the raw materials according to the specified percentage; placing a solvent into a vessel; sequentially adding the lignin removal agent, the degreasant and the softener; and after the lignin removal agent, the degreasant and the softener are dissolved, adding the emulsifier, the penetrant and the protective agent to obtain a liquid product. The pencil board softener is applied as follows: firstly, placing a pencil into a sodium hydroxide solution, and cleaning after soaking for a period of time; then, soaking the pencil board into a softening tank with the pencil board softener, and treating at normal temperature and pressure for 30min to 5h; and finally, taking out the pencil board, cleaning, finishing the softening and denaturation treatment on the pencil board, and drying. The treated pencil board has the characteristics of easiness for peeling and drawing, straight air texture, fine and uniform structure, moderate hardness, small swell-shrink characteristic and the like.