Thermal paints, as a kind of temperature sensor, provided a non-intrusive method for surface temperature measurement. Based on chromaticity theory, the system described in this paper realized thermal paints temperature intelligent interpretation with digital image processing and database technology. The system overcome the effects of subjective interpretation, environment light and human color discrimination ability and made the analysis more accurate and consistent than manual interpretation. The digital image acquisition system was described in detail. Cubic spline interpolation algorithm was adopted to process the data in the L*a*b* color space. The system had been applied to measure the surface temperature of aero-engine combustor. The results showed that the system can greatly improve the accuracy of temperature-recognition.