In order to alleviate the difficulty of determining the upper coal seam, and the poor effect of the lower thick coal seam, the numerical model in the discrete particle flow program (Particle Flow Code, PFC), the numerical model determines the loose medium as the ideal state, and then the specific parameters of the numerical model are set. The initial state of the numerical model includes 3.54 m direct top and 6.1m coal seam, which is divided into 3 m upper coal seam and 3.1 m lower coal seam. Based on the numerical model, follow the principle of “see gangue window” and the control variable method, the design of coal thickness of 2 m, 3 m, 4 m, coal step distance of 0.8 m, 1.6 m, 2.4 m combination test, test different coal thickness and coal step in pairs, a total of 9 groups, in the numerical model, the most reasonable process parameters, 9 sets of test except to adjust coal thickness and coal step, other parameters remain unchanged (including gangue particle size, physical parameters, etc.). The test results show that, When adjusting the coal release thickness, The loss of top coal and coal thickness show the same proportion, And the loss is inversely proportional to the proportion; When adjusting the coal release step distance, the top coal loss and the coal release thickness show the same proportion relationship, The proportion of the loss is in the same proportion, The best process parameters in the numerical model are 2 m coal thickness, 0.8 m coal step distance, After the actual thickness of 2 m in the coal mine, Finding that a higher bracket height is required, May become a potential hazard of construction safety, To optimize the best parameters of the numerical model, Finally, the best process parameters of the composite coal mine are 3 m coal discharge thickness and 0.8 m coal discharge step distance.