To investigate the mechanism of infrared radiation suppression on solid surfaces by spraying water film and to establish an accurate calculation method for infrared radiation, the theoretical and experimental research was conducted to study the influence of water film on the infrared radiation of solid surfaces. The results showed that in the 8-12 μm wavelength range, the infrared radiation characteristics of a solid surface covered with a water film (with a thickness greater than 100 μm) mainly relied on the infrared radiation emitted by the water film. An infrared radiation transfer model was developed to encompass solid surfaces covered by the water film, and the accuracy of commonly used calculation methods in the literature was analyzed. The error in calculating infrared radiation using the free surface temperature of the water film was less than 0.3%, while the maximum error in calculating infrared radiation using the temperature of the solid surface was 8.32%.