The invention relates to the technical field of powder material grading, in particular to a grading method for solid powder. The method comprises the working procedures of ionization, spraying and grading. According to the ionization working procedure, air around an outlet of a spraying pipe is ionized; according to the spraying working procedure, the solid powder is sprayed toward the space between two pole plates through the spraying pipe at the constant speed, the solid powder passes through the ionized air after being sprayed from the spraying pipe, and the solid powder carries positive charges; and according to the grading working procedure, after entering into the space between the two pole plates, the solid powder with the positive charges moves toward one electric pole plate of the two pole plates under the effect of resultant external force and falls on the electric pole plate, the solid powder with the different particle diameters falls on the different positions on the electric pole plate, and continuous grading of the solid powder is realized. The grading method is simple in principle, good in grading effect on the solid powder, high in practicability and suitable for being popularized in the field.