Abstract: Ablation is one of the main means of thermal protection for hypersonic flight vehicles. In this paper, based on pyrogeneration plane ablation model and temperature measurement at some specific locations, the surface heat flux estimation method is developed with adjoint equation analysis and validated by numerical examples. It is shown that the estimated heat flux agrees with the exact value well, and the difference between the estimated heat flux and the exact value grows as the measurement noise increases. It is also revealed that the measured noise in the ablated surface recession value may have a significant influence on the estimated heat flux. Furthermore, the estimation method is utilized to analyze the experimental ablation results of the blunt Carbon phenonic material Narmco4028 in ceramic heated tunnel, it is found that the estimated surface heat flux value is close to the heating power of the archeater. This result further verifies that the estimation method is effective and may have a bright prospect in engineering practice.