Abstract: To investigate the effect of temperature on the contact angle of water droplets on polydimethylsiloxane （PDMS） films, a self-built high-temperature and high-pressure sessile-drop visualization system was adopted in this study. Combined with the low-bond axisymmetric drop shape analysis, the morphologies of water droplets on the PDMS surface were systematically captured, and their corresponding contact angles were accurately measured at a constant pressure of 5 MPa over a temperature range of 30–210 °C. The experimental data revealed that the contact angle remains essentially constant at ~96° throughout the entire temperature range, exhibiting negligible temperature sensitivity. On the theoretical side, the water-PDMS interaction was represented by a Steel 10-4-3 potential, with the water-PDMS attraction energy treated as an adjustable parameter. After calibrating this parameter to the experimental contact angle at a single arbitrary temperature, classical density functional theory combined with Young’s equation was used to predict the contact angle evolution. The calculations indicated a slight increase in the contact angle with temperature at low temperatures, followed by a pronounced decrease at higher temperatures, a trend that deviates from the experimentally observed plateau. This discrepancy suggests that the interaction potential requires further refinement. The present work not only enlarges the high-temperature, high-pressure contact angle database for water-solid systems but also provides a valuable guidance for future theoretical development.