Abstract: The vertical inhomogeneous particle concentration in a large-space machining workshop with a displacement ventilation system will increase the required ventilation volume for indoor particle concentration reduction. The present work presents a particle concentration prediction model using a zonal modeling method that can rapidly predict the vertical particle concentration distribution for the energy-saving performance analysis of the ventilation system. The model, which takes the wall heat plume zone, heat source heat plume zone, and main airflow zone into account, can obtain the inter-regional airflow based on the energy balance and continuity equations and predict the zonal particle concentration based on the mass balance equations using particle emission rates and inter-regional airflow. A validation experiment conducted in a scaled chamber demonstrates that the relative error of the prediction model is less than 20%, it shows that the model can basically meet the engineering requirements. Further study of the prediction model by a case study under five particle emission conditions showed that the required air volume supply can be reduced by 18.83% to 44.41% compared to the traditional method used on variable air volume system. Overall, the prediction model can accurately and rapidly predict the vertical particle concentration distribution in large-space machining workshops under displacement ventilation, showing promising prospects in optimizing the performance of the ventilation system.