The utility model relates to a straw powder ration spraying device that becomes thoroughly decomposed comprises material storehouse and row's feed bin, and last casing, the lower casing of row's feed bin solidify as an organic wholely by fixing bolt no. 2, the material storehouse is fixed on last casing by fixing bolt no. 1, the built -in stirring propeller in material storehouse, the stirring propeller is driven by gear motor no. 1, arrange the built -in screw axis of feed bin, the screw axis is driven by gear motor no. 2, has helical blade on it, there are discharge gate, gear motor power connection chain in the casing lower part down. During the use, fertilizer adds to the material storehouse with the agent of becoming thoroughly decomposed, watering concrete gear motor power, beating breakdown gear motor no. 1, the stirring propeller advances the material whereabouts to arranging the feed bin, to certain packing rate, opens gear motor no. 2, and the epaxial helical blade of spiral further mixes the material, constantly mixes, constantly advances, constantly follows the discharge gate ejection of compact. The utility model discloses simple structure can use convenient to use with other agricultural machinery are supporting, can even quantitative spraying, can reduce the amount of application, it is with low costs, be favorable to the environmental protection.