With CFD as auxiliary tool, conducts an analog design for ISO7 clean airflow in the key coating workshop of PCB process, uses the software of Airpak for the solution and compares the simulated data with the measured data. The results show that due to the impacts of people and logistics flows, the simulation data deviates from the measured, but it is basically accurate. Numerical simulation helps designers to choose the right air flow and temperature-humidity field.