The transmittance of slime water is one of the more important evaluation indexes for slime water treatment. This study analyzes the importance of cooperative treatment on the slime water by microbial and chemical reagents and tests of its basic properties. A model equation and theoretical analysis are provided through experimental work, model analysis and data processing. In addition, the micro effect mechanism of the cooperative treatment is explained. The experimental results demonstrated that the experimental slime water has a high content of fine mineral particles with particle size of less than 20 mu m in 85% slime water. Particles with size of less than 5 mu m take up half the content of the slime water. Since most coal slurries are SiO2, Al2O3 contained clay minerals, it is easy for them to form colloidal particles with strong negative charges. The content of slime ash in the slurry is very high, resulting in difficult settlement of mineral particles. Using the experimental data, a quadratic model equation is built employing the transmittance of the supernatant of slime water as response index. This equation points out the optimum quantity of the microbial reagent. In addition, it was found that both the microbial reagent and polymer flocculant interact with CaCl2 obviously. The theoretical analysis explains the micro separation mechanism for mineral particles and water-solid-liquid mixture. The addition of microbial reagent disrupts the charge balance of the slime water and CaCl2 increases the coagulation effect. The polymer flocculant produces highly effective flocculating settlement. The three reagents have a synergistic effect on slime water and achieve an ideal transmittance of 92%.