An improved mass model with only two parameters for coarse coal particles using image analysis was established. Five variables density, projected area, perimeter, length and breadth of the best-fit-rectangle, were used for the initial mass model. Due to the discovery of some relationships between the variables, the improved mass model only consisted of projected area and density and was established with a satisfied accuracy. Simultaneously, the computation speed of improved mass model is 5 times more than that of initial mass model. When tested 50 times against a different batch of modeling sample, the total relative errors of the improved mass model were less than 6%, however, the relative errors of 25-50 mm were less than 7% and that of other size fractions were less than 5%. Experimental results revealed that only projected area and density were required to develop such model with satisfactory results. A promising application of this mass model will improve the on-line control of coal industry. (C) 2012 Elsevier B.V. All rights reserved.