Abstract: In order to make full use of complementary energy of overflow pipe in hydrocyclone, energy recovery device which installed in overflow pipe port is designed by using the principle of turbine power generation.To study the effects of its residual energy recovery and the classification effect of hydrocyclone, clear water test, power generation test and coal slime grading test are respectively carried out.The test variables are feed pressure, overflow pipe diameter and impeller blade angle.According to the results of clear water experiment, feed pressure and rotor speed relation graph is drawn.It shows that impeller speed increases with the increase of feed pressure, and the optimal blade is 20°.At the same time, the impeller is used for power generation test, which verifies that the residual energy recovery device can effectively convert the mechanical energy into electrical energy.Through fines grading test when the feed pressure is 0.14 MPa and the overflow pipe diameter is 40 mm, the optimal blade is 15°, and there has no effect on the classification effect of hydrocyclone in this feed pressure.