The utility model belongs to a continuous elutriation instrument used in reselection, and particularly relates to an improved continuous elutriation instrument capable of dividing wider particle swarms into particle swarms with narrower particle sizes including 74 mu m, 37 mu m, 19 mu m, 10 mu m, 5 mu m and minus 5 mu m. Under the conditions that the corresponding water supply quantity is 105 ml/min and the soluble glass solution supply quantity is 5 ml/min, the grading section area of each grading tube of the continuous elutriation instrument is increased by about 83% than the grading section area in the technical background, and the inner diameters of upper and lower conical short tubes, used for connecting latex tubes, of each grading tube are doubled than the original inner diameters. According to the improved continuous elutriation instrument, the conventional particle swarm grading technology and theory are not changed, the hindered settling phenomenon produced in the grading tubes can be greatly improved, further, the blockage phenomenon frequently produced in the area where the lower conical short tube is connected with the latex tubes can be eliminated, and accordingly, the follow-up grading accuracy is greatly improved.