The invention discloses a new macromolecule fiber composite material which is prepared by the following components in parts by weight, 40-100 parts of plant fiberfill, 60-100 parts of plastic base material, 3.5-5 parts of heat stabilizer, 1-2 parts of plasticizer, 1.6-2 parts of lubricating agent, 4-8 parts of modifying agent, 1-3 parts of compatilizer, 2-3 parts of coupling reagent, 1-5 parts of super dispersing agent, 1-4 parts of positive ion surface active agent, 1-1.8 parts of foaming agent, 1-5 parts of blowing promoter, 0.3-1.2 parts of antioxygen, 1-10 parts of cross-linking agent, 1-20 parts of nucleating agent, 0.8-1 part of viscosity reducer, 0.8-1 part of tackifier and 3.2-13.4 parts of other auxiliaries. The new composite material can not easily cause wet swelling and air shrinkage, and is low in expansibility and water absorbability, so that the prepared product has good stability.