Based on increasingly coal slime content of raw coal leading to increasingly content of fine grained material and reduce grading efficiency problem, Xingtai Mine explored the technology from affecting the structural parameters of the cyclone classification effect, operating parameters and the material properties, solved the closed-circuit circulation system, optimized the technological process. the practice showed that the optimization of the technology by modified cyclone and the technological process, which improved vortex bottom flow problem of fine and the classification efficiency of cyclone. under the same classification parameters, through the transformation, CSS overflow ash content reduced from 23.08% to 18.04%, +0.18 mm gain size rate improved from 59.96% to 75.29%, underflow ash increased by 7.90%, with obvious effect.