Water mist environment, which is very common in industrial production, has a strong attenuation effect on infrared radiation. The artificial water mist system is often used in the cooling device of continuous casting slab in secondary cooling zone, and it is of great significance to accurately measure the slab surface temperature in the secondary cooling zone of continuous casting to improve the stability of product quality. In view of the interferenceof a large amount of water mist in the secondary cooling zone on the non-contact temperature measurement of continuous casting slab surface, a correction method based on Mie scattering theory is proposed. Firstly, according to the air-water nozzle used in the field, the simulation experiment is carried out to analyze the flow distribution of the water mist, and the water mist state model is established. Then the attenuation characteristics of the infrared radiation under the water mist state model is analyzed, the corresponding extinction coefficient is calculated through the simulation experiment, and the correction factor of the infrared radiation attenuation is obtained by using Lambert Beer law. Finally, the correction factor is introduced into the non-contact infrared temperature measurement system to correct the real-time temperature value. The research shows that the accuracy of the non-contact infrared temperature measurement system can be effectively improved by introducing the correction factor.