This paper introduces the research results to determine the reasonable structure for the combustion chamber of the pulse-jet fogger to increase efficiency and improve the operating performance of the machine applied in disinfecting pigsties in Vietnam. The 3D model of the combustion chamber - nozzle was designed using CATIA software, used ANSYS FLUENT software was used for simulation analysis. The parameters of airflow velocity at the nozzle outlet center, pressure, and temperature inside the combustion chamber were analyzed based on the simulation results of 04 test models; then, experiments were carried out with 02 actual models to verify the simulation results. The simulation results show that the above parameters depend on the size of the combustion chamber - nozzle length. After the experiment, a reasonable combustion chamber-nozzle model was selected for the pulse-jet fogger to improve the operating performance of the machine.