The invention relates to a graded screening machine for live fishes. The machine comprises a horizontal swing mechanism, a fish entering bucket and fish collecting buckets which are mounted on a rack as well as cam adjusting plates, wherein the horizontal swing mechanism comprises a plurality of grids, adjusting doors mounted between adjacent grids as well as a cylindrical side wall fixedly connected to the outer edges of all grids; a cam mechanism and a spring return mechanism controlled by the cam mechanism are mounted, corresponding to each adjusting door, at the outer side of the cylindrical side wall; the cam mechanisms are adjusted by the cam adjusting plates to rotate; and the rotating shafts of the adjusting doors are driven by the spring return mechanisms to rotate so as to form gaps with set sizes between the adjusting doors and the adjacent grids. According to the graded screening machine provided by the invention, in a rotating process of the horizontal swing mechanism, live fishes can be quickly and accurately distinguished according to the sizes and different specifications of fish bodies and are collected into the corresponding fish collecting buckets, so that the grading efficiency of the live fishes is improved.