The invention discloses a modified natural fiber-based ultrafine granular material. The modified natural fiber-based ultrafine granular material is characterized by comprising, by weight, 10 to 15% ofnatural fiber powder, 40 to 60% of deionized water, 1 to 1.5% of hydrogen peroxide, 0.8% of a coupling agent, 10 to 15% of a thermoplastic high polymer and 0.1% of paraffin. According to the invention, hydrogen peroxide and the coupling agent are employed for surface modification of natural fibers, so the interfacial compatibility of the natural fibers is improved; then the natural fibers and thehigh polymer material are subjected to thermal compounding, mixing and granulation, so the problems of difficulty in blending of the natural fibers and the high polymer material, easy degradation ofthe natural fibers and the like are overcome; so the utilization rate of the raw material, i.e., the natural fibers, is effectively increased, the problem of shortage in petroleum resources is effectively alleviated, and the problems of difficulty in degradation and great pollution of plastic products, rubber products and paint products are overcome.