The invention discloses biomass-based thermoplastic elastic master batch. The biomass-based thermoplastic elastic master batch is prepared, by weight, by the following raw materials of 50-70 parts of biological powder, 5-10 parts of biolipid, 3-8 parts of plant fibers, 8-20 parts of polyurethane, 4-10 parts of hide glue, 8-20 parts of capacity-increasing plasticizer, 0.5-5 parts of grafting coupling agents and 0.5-5 parts of functional auxiliaries. According to the biomass-based thermoplastic elastic master batch and a preparation method thereof, the biomass-based materials such as the biological powder, the biolipid and the plant fibers are adopted to serve as the main raw materials to prepare the elastomer material, screening and optimizing are conducted on the biomass-based material, the preparation technologies such as modification and crosslinking copolymerization are combined, and the prepared biomass-based thermoplastic elastic master batch has better biodegradability. Sources of the selected raw materials are rich, the cost is low, consumption of petroleum can be effectively reduced, and the biomass-based thermoplastic elastic master batch is environmentally friendly; the forming technologies are combined by adopting general processing equipment, and industrialized application and popularization are convenient.