Abstract: This paper introduces the working principle of Passive Containment Cooling System（PCS） following a design basis accident.A flat-plate test bench and the accompanying measurement system are designed to study how the counter-current air affects the water film on the containment surface.Two key experiment parameters,flat-plate spacing and probe positions,are calculated and analyzed through fluid mechanics,experimental characteristic and experience correlation.The analysis results show that the experiment plan is reasonable and feasible,and it is proper when the flat-plate spacing is 150 mm and the probe position of the first rank is 1 m away from the flat-plate upside.