The invention discloses a mechanical device for removing dust on seeds. The mechanical device comprises a dust removal chamber and a material inlet pipe, the material inlet pipe is inserted into the upper portion of the dust removal chamber and extends into an inner cavity of the dust removal chamber, a rotary plate is correspondingly arranged on the lower portion of the material inlet pipe, and the rotary plate is in rotational connection with a motor. The motor is fixedly connected with the inner wall of the dust removal chamber through a connection rod, a plurality of baffles are connected with the inner wall of the dust removal chamber, one end of a dust collection pipe is connected with the lower right portion of the dust removal chamber in a penetrating mode, and the other end of the dust collection pipe is connected with a dust collection box in a penetrating mode. The mechanical device for removing the dust on the seeds is simple in structure; the seeds obtain greater kinetic energy by adding a combined structure of the rotary plate and the baffles, driving the rotary plate to rotate through the motor and using the centrifugal force, so that the collision capacity of the seeds on the inner wall of the dust removal chamber is improved, moreover, the number of collision times is increased by adding the baffles, the two aspects are combined with each other, the seeds are more easily separately from the dust, soil and other impurities, the dust removal rate of the seeds is further improved, and the quality of the seeds is improved.