The invention discloses a tea biomass composite material and a preparation method and application thereof. The tea biomass composite material is prepared from the following raw materials in parts by weight: 60 to 70 parts of tea biomass, 20 to 50 parts of wood meal, 12 to 30 parts of straw powder, 2 to 5 parts of compatilizer, 0.2 to 1.5 parts of lubricant, 2 to 3 parts of coloring agent, 0.1 to 3 parts of antioxidant and 0.1 to 3 parts of stabilizer. The preparation method comprises the following steps of weighing the raw materials according to requirements; soaking the tea biomass for 20 to 48h at the temperature of 60 to 80 DEG C, cleaning, airing, and crushing to 10 to 20 meshes for further use; mixing the tea biomass treated in step 2 and the wood meal, the straw powder, the compatilizer, the lubricant, the coloring agent, the antioxidant and the stabilizer, uniformly stirring, and feeding into a granulating machine for granulating at the temperature of 60 to 118 DEG C, so as to obtain a master batch; feeding the master batch into an extruding machine, and extruding, so as to obtain the tea biomass composite material. The tea biomass composite material has the advantages that the mechanical property is good, the sterilizing and bacteria-inhibiting ability is strong, the moisture absorbing ability is realized, and the tea biomass composite material is suitable for serving as an outdoor floor and furniture material.