In order to solve the problem of slime water settling treatment in wet coal washing and provide a better separation basis for the subsequent slime separation and the performance of auxiliary process, the influence of slime size, density class and solid content on the rheological properties of slime water were mainly studied through the indexes of apparent annual viscosity and slime water settling filtration characteristics, and four different types of slime water flocculant were selected to explore the effect of flocculant on slime separation. The results showed that the apparent viscosity of slime suspension increased with the decrease of coal particle and density, and increased with the increase of solid content. Non-ionic polyacrylamide flocculant exerted little effect on the apparent viscosity of slime suspension, with good sedimentation and filtration characteristics. Adding anionic polyacrylamide flocculant, with the worst sedimentation and filtration property, while adding cationic and amphoteric polyacrylamide flocculant had an effect on the sedimentation and filtration characteristics of the suspension between non-ionic and anion.