This invention relates to a venturi smoke-free vertical steam boiler, a thermal equipment, including shell, curved pipes and combustion devices, the outside bending pipes is placed in the box, between the introvert pipes form a hot gas cavity, beneath the cavity is the combustion chamber, beneath the combustion chamber is the grate, beneath the grate is the ash chamber, on the combustion chamber has stove door to coal, and on the ash chamber has a gray ash doors, ash chamber is equipped with a tuyere, on the top of combustion chamber has narrow high temperature gas export, above the export has a secondary combustion chamber, the cross section of the secondary combustion chamber is circular, the secondary combustion chamber has a secondary tuyere, on the top of the secondary combustion chamber has high temperature gas export, the high temperature gas export connect hot gas chamber. A rational structure, solve the problem of coal-smoke emission, carry out smokeless emission, high thermal efficiency, conservation of coal resources and the environment.