This study examines the condensation behavior of superheated water vapor within a swollen polymer brush, specifically under conditions of pure water vapor and in the presence of non-condensable gas (NCG), utilizing a grafted PNIPAM nanopolymer brush model. The investigation employed the grand canonical Monte Carlo method in conjunction with molecular dynamics simulation (GCMD). A systematic analysis of the underlying condensation mechanism was conducted, revealing the synergistic regulatory effects of temperature, pressure, and time scale on the phase transition behavior of water molecules. Additionally, the influence of NCG on condensation performance was assessed. The results demonstrate that thermosensitive gel materials can effectively mitigate the negative impact of NCG on water vapor condensation. These findings provide a critical theoretical foundation for improving the performance of thermosensitive materials in practical operational settings.