The invention relates to a fuzzy closed circuit self-turning dynamic hydraulic cyclone classifier which is characterized by comprising a reducing underflow pipe, a tapered cylinder body, a slurry inlet pipe, sealing rings I, a valve, a slurry inlet particle size analyzer, a slurry inlet pressure gauge, a slurry inlet flowmeter, a reducing pipe, a control computer, an overflow cylinder body, a motor, a bearing, a sealing ring II, a bearing cover plate, an overflow pressure gauge, an overflow flowmeter, an overflow particle size analyzer, an overflow pipe, a cylinder body, a center shaft and an impeller. The classifier can achieve an optimal classification effect by replacing the reducing underflow pipes with different diameters according to the particle size composition properties of different minerals, can improve the rotating separation strength of slurry body particles in the cylinder body, and is high in automation degree and control precision, and good in classification effect.