The invention relates to the technical field of paper folding processes, in particular to a paper folding method of door closing folding. The paper folding method comprises the following process steps: an arc hole guide block, a U-shaped hole guide block, a return hole guide block, a strip hole guide block and a V-shaped hole guide block are arranged on a horizontal guide rail in sequence; a starting end of a paper slip penetrates through the arc hole guide block, the U-shaped hole guide block, the return hole guide block, the strip hole guide block and the V-shaped hole guide block in sequence; the starting end of the paper slip is pulled, and firstly, the paper slip passes through the arc hole guide block to be folded to an arc shape; then, the paper slip passes through the U-shaped hole guide block to be folded to a U shape; then, the paper slip passes through the return hole guide block to be folded to a return shape; then, the paper slip passes through the strip hole guide block to be folded to a strip shape; then, the paper slip passes through the V-shaped hole guide block to be folded to a V shape; and the door closing folding of the paper slip is finished. The paper folding method not only can save the manpower, improve the production efficiency and reduce the production costs for enterprises, but also can satisfy the production under different environments.