Abstract: In order to realize automation calculation of medium flow in coal preparation process design,based on the characteristics of medium flow calculation,the special treatment is used on the sequential modular approach to meet the need of calculating order. Then the calculation order is searched to analysis and determine all parameters for the split flow calculation. Finally the formula is applied to end calculation. The results show that the method based on sequential modular approach can not only ensure the equilibrium error of the medium system to meet the design requirements,but also can realize the automation of the medium flow calculation,and save manpower,material resources,time and other resources