The invention discloses a method for forming a biomass fuel and particularly relates to a method for forming a biomass fuel by using plant straw, wood flour, shrub, grass and the like as raw materials. In the method, biomass, coal dust and kieselguhr are used as raw materials and are crushed, mixed and compressed to be formed. The stable calorific value of biomass of different types and from different places can be obtained by adjusting the mixing ratio of coal to the biomass; under the condition of rated stable working conditions of a boiler, the influences of alkaline corrosion on the biomass are eliminated, the bonding forming of the crushed biomass particles is promoted effectively, the formed particles have high physical quality and properties, the compression forming rate is improved and energy consumption for forming is reduced. The biomass fuel of the invention can make full use of the straw, wood flour, shrub and grass and other wastes, and helps to reduce the demands for coal, natural gas and other non-renewable energy resources and relieve environmental pollution caused by combustion; and the biomass fuel has the advantages of improving volumetric heat release rate of the boiler and furnace temperature, improving thermal efficiency of the boiler, along with stable calorific value, alkaline corrosion resistance, quick ignition, high combustion efficiency, and the like. The biomass fuel can be used in biomass combustion power generation, and thus, the problem caused of lack of regional biomass that at present biomass power generation cannot be performed continuously and stably.