NOVELTY - Mixed biomass fuel, prepared from semi-finished material comprising fine coal (70-80 wt.%), woody fine material (0-30 wt.%), herbaceous hollow fine material (0-30 wt.%), and herbaceous solid fine material (0-30 wt.%), is claimed.    USE - The mixed biomass fuel is in a coal-fired power plant.    ADVANTAGE - The mixed biomass fuel is cost-effective, safe and reliable in use without polluting the equipment or the environment.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparing mixed biomass fuel, comprising preparing fine coal by selecting volatile phenol having at least 30, heat value of higher than 550 kcal and the moisture level of less than 6%, removing ferric by firstly breaking into broken coal to less than 1 cm, performing dry washing and screening to control the moisture to be lower than 4%, secondly breaking into the broken coal to less than 60 meshes to obtain the semi-finished product as fine coal; preparing woody fine material by selecting wood offal, branches and shrub of plants and the earth respectively, removing the earth and removing the ferric, firstly breaking into crude broken material at 1 cm, secondly breaking into the fine material having less than 1 mm, keeping the moisture level of at most 1%, using the secondly broken fine material having less than 1 mm with the moisture level of at most 1% as the semifinished product as the woody fine material; preparing the herbaceous hollow fine material by selecting herbaceous plants of hollow straws of flax, wheat and red bean, respectively, removing the earth and the ferric, firstly breaking into the crude broken material at 1 cm, secondly breaking into the fine material having less than 1 mm, keeping the moisture level of at most 1%, using the secondly broken fine material having less than 1 mm with the moisture level of at most 1% as the semifinished product of herbaceous hollow fine material; preparing the herbaceous solid fine material by selecting herbaceous plants such as solid straws of sunflower, corn and broomcorn, respectively, removing the earth and the ferric, firstly breaking into the crude broken material at 1 cm, secondly breaking into the fine material smaller than 1mm, keeping the moisture level of most 1% using the secondly broken fine material having less than 1 mm with the moisture of at most 1% as the semi-finished product of the herbaceous solid fine material; preparing the fine mixture by selecting the fine coal, the woody fine material, the herbaceous hollow fine material and putting the fine material to uniformly mixing the fine material to obtain product as the semi-finished product; milling the uniformly mixed fine mixtures and mixing uniformly, controlling the fineness to less than 160 meshes and controlling the moisture level to at most 3%, obtaining the qualified mixed biomass fuel; and packaging by packaging the qualified mixed biomass fuel by a special device and a special package box.