Abstract: Through the liquid film rupture model and the reduce of Navier-Stokes (N-S) equation and continuity equation for the 2-dimensional boundary layer in the curvilinear coordinate system, with non-dimension definition, the theory method for calculating the critical airflow velocity of water film breakdown is obtained; and, applying the Planar Laser Induced Fluorescence (PLIF) method and image processing method, the relationship between the water film thickness and the critical airflow velocity of water film breakdown is investigated through the water film breakdown experiment. Both experimental and theoretical calculation results show that the critical airflow velocity of water film breakdown is negatively correlated with the water film thickness. With the same water film thickness, the larger the critical breakdown structure parameter of corrugated plate dryer is, the greater the critical airflow velocity of water film breakdown is, which is beneficial to the improvement of the steam-water separation effect.