The liquid film cooling technology in rocket engines plays a crucial role in the thermal protection of combustion chambers, directly affecting the performance and reliability of rockets.Accurately evaluating the effectiveness of coolant is fundamental to ensuring manned spaceflight safety and a key to achieving rocket reusability. To precisely calculate the effects of design parameters on the heat transfer performance of the combustion chamber, a heat transfer model was established. The accuracy of the model was verified through experiments, and the effects of flow rate and temperature of the coolant on the liquid film/gas film were analyzed based on engineering prototype. The results show that: the error between the model results and experimental results is less than 2%, allowing clear determination of fluid parameters during different states of the coolant. The effectiveness of liquid film in the thrust chamber is simultaneously positively influenced by injection flow rate and negatively affected by injection temperature, and the variables that produce equivalent effects are approximately 0.1 kg/s and 20 K. The performance of gas film can be characterized by its cooling efficiency, andwhen the cooling efficiency changes by 0.02 (based on 0.68), the length of the gas film varies by 4%.