The wet grinding of iron ore powder was investigated using a stirred media mill. In this study, the fitting degree of four cumulative undersize distribution functions was compared and the parameters of the four functions were discussed. It was concluded that the particle size distribution (PSD) of grinding products followed well with the Rosin Rammler Benne (RRB) function. In addition, operational parameters such as ball filling rates, stirrer tip speeds and grinding time have been investigated in terms of the width of PSD and specific energy input. The results indicated that slight differences in the width of PSD could be observed at different ball filling rates and stirrer tip speeds. It was also found that increasing the ball filling rate and stirrer tip speed could improve energy efficiency. Furthermore, an equation was established to predict PSD based on the characteristic particle size of the RRB function and size-energy model, which provided a sound fit to the grinding products under various grinding conditions (C) 2020 Published by Elsevier B.V.