The changing law of tristimulus value of temperature indicating paint film color with respect to temperature under the condition of invariable film thickness and baking time was analyzed,that based on the correlation analysis of color tristimulus values,so as to construct a piecewise function model with film thickness as the condition.Then,the planning is constructed from the perspective of inverse problem,so that the predicted temperature value of the model is closest to the actual baking temperature value.Finally,the experimental data are used to estimate the parameters of the model,and the optimal solution is obtained by numerical algorithm.The experimental results show that the interpretation result of the model is better than that of the manual interpretation.