Abstarct: One of the main parameters that determine the quality of coal, is the ash content. Ash existence in coal increases the reagent consumption, causing problems in the steel production process, increases oxidation of coke and ultimately reduce the sensitivity and efficiency of furnaces. Flotation due to the natural hydrophobic particles of coal is one of the best methods to reduce the ash content in coal. Preparing the surface of the particles for preforming chemical reactions increases the flofation efficiency. Applying ultrasound is widely effective for surface preparation and cleaning processes. Therefore, In This research the impact of ultrasound in improving the efficiency of coal flotation, were studied. By taking the effectiveness of ultrasonic waves in cleaning the surface of coal particles and determination of the operating parameters, experiments were designed using the Taguchi method. The results were analyzed by software. Determining the optimum values for each parameter by software, the validation experiments were performed. The results were well correlated with predicted values by software. The results showed that the use of ultrasound can reduce the ash by 45 percent, increase the separation efficiency by 17 percent, 65 percent reduction in the collector, 50% in frother reduction, 50% reduction in time. Also ultrasonic waves can be used for increasing temperature in flotation process.