This paper analyzed the dynamic state of the water ring, which is formed through the exothermic process of steam condensation, and its influence on heat transfer during the operating process of the high speed paper machine’s drying cylinder. The influence of perturbation on the flow condition of the water ring was also discussed. This information was used to design the steam-knife gas supply system in the drying cylinder. This system provides a so-called steam-knife to attack the water ring, which would change the dynamic state of the water ring’s fluid level. This would ultimately improve the heat transfer efficiency.