ABSTRACT The effect of air dissolved in natural water on simultaneous ultrasonic-assisted coal flotation was investigated combined with flotation tests, froth properties and flotation kinetics models analysis. Compared with degassed water, the better flotation performance was obtained in natural water when ultrasound was not used or ultrasonic power was lower than 200 W. For the low ultrasonic power (< 200 W), the air dissolved in natural water promoted the precipitation of bubbles to obtain the small bubble and thick froth layer, which was beneficial to improve the coal flotation. However, the froth properties in natural water were almost the same as those in degassed water if the ultrasonic power was reached to 200 W, indicating that the performance of ultrasonic flotation in degassed water was almost the same as that in natural water. In addition, the processes of ultrasonic-assisted coal flotation in natural and degassed water could be described by the second-order model with rectangular distribution of floatability. The ultrasonic flotation rate of natural water was twice than that of degassed water. Hence, these above results made a contribution to improve the performance of ultrasonic-assisted coal flotation in natural water.