The invention relates to a fire fighting bomb for an unmanned aerial vehicle. The fire fighting bomb comprises a spherical shell, wherein the spherical shell is composed of an upper hemispherical shell and a lower hemispherical shell, and the upper hemispherical shell and the lower hemispherical shell are filled with a dry powder extinguishing agent; a gunpowder bag is arranged between the upper hemispherical shell and the lower hemispherical shell and is connected with a firing line; a plurality of crossed annular grooves are formed in the outer surface of the spherical shell, and the firing line goes through the spherical shell and then is fixed in the annular grooves. The fire fighting bomb adopts the spherical structure. When the fire fighting bomb is impacted, is shot or falls to the ground, the spherical structure can uniformly decompose force to a spherical surface, so that the fire fighting bomb sphere cannot be ruptured. The firing line is adopted to detonate the gunpowder bag, and the dry powder extinguishing agent is injected to the surrounds at the moment of explosion of the gunpowder bag. The fire fighting bomb has the effects of high fire fighting speed and high fire fighting efficiency.