The treatment of slime water not only has a direct impact on the economic benefits of the coal preparation plant, but also has an important significance for the conservation and utilization of the environment and water resources in the mining area. However, under the background of increasing mechanization level of coal mining, the proportion of fine coal is increasing, and the slime water exhibits fine, high and sticky characteristics in terms of particle size, ash, and viscosity, making it difficult for the slime water to settle. In this paper, research on the treatment of difficult-to-settle slime water by ultrasound-electrochemistry is investigated. The principle of the ultrasonic-electrochemical method for treating difficult-to-settle slime water is discussed. The effects of electrodes, electrolytes, ultrasonic energy density and ultrasonic time on treatment of difficult-to-settle slime water are analyzed. Results show that ultrasound-electrochemical pretreatment for difficult-to-settle slime water is not a simple superposition of the two treatment methods, and ultrasound can promote the electrochemical reaction. The optimal ultrasonic parameters are given: ultrasonic frequency, energy density and ultrasonic time are 29 kHz, 0.5 W/m and 4 min respectively. Based on the basic properties of the micro-charge on the surface of coal particles, the flocculation sedimentation can be promoted effectively by the combination of sonochemical and electrochemical methods. Finally, the research status of the new treatment technology for difficult-to-settle slime water is discussed, and the development trend is pointed out.