The invention belongs to the field of high molecular materials, and particularly relates to a low-hardness polyurethane self-skinning composition for a printing rubber roll and a preparation method for the composition. The composition is prepared by mixing a component A and a component B according to the mass ratio of 100:(30-35), wherein the component A is prepared from polyether polyol, polymer polyol, a chain extender, a foaming agent, a foam stabilizer, a hole opening agent and a catalyst, and the component B is prepared from polyether polyol, pure MDI, liquefied MDI and crude MDI. The prepared composition not only has the advantages of being good in hand feeling, wear resistant, shock resistant, simple and convenient to produce, and the like, but also is compact and smooth in surface and wide in hardness adjustment range. The composition can be used for manufacturing the low-hardness rubber roll in the printing industry, and the printing rubber roll prepared by adoption of the composition is not only relatively low in hardness, but also better in elastic resilience, wear resistance and shock resistance. The invention further provides the preparation method for the composition, and the process is reasonable.