The invention discloses a room-temperature low-pressure preparation method of biomass granules. The room-temperature low-pressure preparation method of the biomass granules comprises the following steps: taking one or more biomasses of dried and pulverized sawdust, straws, rice husk, wild herbaceous plants or leaves as raw materials and natural plant fiber or synthetic fiber as an enhancer; uniformly mixing the enhancer fiber with the length range of 0.1-50 mm and the dried and pulverized biomass raw materials according to a weight ratio of 1: 100-100: 1; and processing the mixture into the biomass granules at a temperature of 5 to 50 DEG C and a pressure of 0.1-10 MPa. By adopting a room-temperature low-pressure process, production equipment and a production process are simplified, and the energy consumption in the production and the production cost are reduced; the biomass granules prepared by the preparation method have the advantages of high density and high strength and are convenient to transport, store and feed; and the biomass granules have the advantages of high calorific value and low pollutant emission in a combustion process, and the like, so that the problems of energy crisis and environmental pollution are effectively solved.