The invention relates to a solid fuel diesel, which is an explosive motor burning solid fuel powder (such as plants, coal, etc.), and the performance (including the convenience of fuel employment) is similar to a piston diesel, wherein water is used as working substance to realize the conversion from pressure energy to mechanic energy without a bent axle or a piston; the solid fuel diesel can function as power for engineering machines, vehicles and vessels; the manufacture cost is low; the vibration is low; the efficiency is high; and the service life is long. The theory and structure of the whole machine are introduced in the specification.