Abstract: The method of chromatic thermometry was introduced into the on-line thermometry of ceramic sintering. The thermometry system was designed according to Planck law. The calculation methods of key parameters, such as wavelength, emissivity, rate of conversion, were presented. The relation between wavelength and energy/sensitivity was comprehensively analyzed. The prototype was set up and tested according to the characteristics of ceramic sintering process, and the results indicated the metering error was less than 10 K during 1 300 K～2 000 K.