For the problem that the actual flow detection value of the screw feeder differs greatly from the calculation value of the traditional calculation formula, an RSM eperimental design is used to modify the flow calculation formula of the screw feeder. Considering the complexity of the actual test, the ratio of the flow value measured by the discrete element simulation and the value calculated by the calculation formula is used as the response, and the RSM experimental design is designed by taking the screw pitch, speed, and pipe diameter that significantly affect the flow difference as the factors. The second-order regression equation between the factors and the response value, from which the flow calculation formula of the screw feeder is further obtained. In order to verify the feasibility of the flow calculation formula, the SolidWorks software was used to establish a three-dimensional model according to the design requirements, and the EDEM software was imported for discrete element simulation. The flow value obtained from the simulation was found to be 1.258 t/h. The error of the calculated flow value of 1.210 t/h with the correction formula is 3.97%, indicating the rationality of the flow correction calculation formula and providing a reference for the design calculation of the screw feeder.