Taking the large-scale bag filter at the preheater of a 10 000 t/d cement production line as an example and carry out CFD simulation based on the boundary contour method technology. Analyzing the calculation results, we put forward the correct optimization structure, and improve equipment operation status. Firstly, the calculation steps of the boundary contour method were introduced. Secondly, numerical simulations were conducted on the entire machine and single bag chamber of the equipment to analyze and compare the distribution of flow volume in each bag chamber, and using the boundary data of the corresponding bag chamber inlet, calculate and analyze the flow field state of the single bag chamber, and propose a reasonable plan to optimize the internal structure. Simulation analysis found that arranging high-efficiency guide plates at the ash hopper and reasonably arranging grid plates on the side of the filter bag are the optimal structural optimization solutions for the bag filter. Application practice has shown that using the boundary contour method based on CFD numerical simulation technology can accurately simulate the internal airflow state of equipment with complex structures and multiple components, ensuring that the equipment achieves good operating conditions.