• A multi-spectral thermal imager for laser-induced damage temperature field is developed. • A five-channel four-wavelength filter photometer is designed to satisfy multi-wavelength measurement. • Based on the multi-spectral thermometry, the laser-induced damage temperature field was measured by multi-spectral thermal imager. • With the increase of damage time, the temperature field in the central region tends to be stable, and the temperature field in the edge gradually diffused. In order to analyze the damage effectiveness of the high-energy laser beam damage to the target, it is important to accurately measure the laser-induced damage temperature field. However, the obtained data cannot meet the requirements of damage effectiveness evaluation, as most of these data are from simulated temperature measurements in the laser-induced damage temperature field. Moreover, traditional temperature measuring instruments can only measure temperature points, and cannot obtain the multi-spectral temperature field of the laser-induced damage. In response to the above problems, this paper has developed a multi-spectral thermal imager for measurement of the laser-induced damage temperature field. Using a five-channel four-wavelength filter photometer, the instrument makes the fifth channel as a calibration channel so that the infrared thermal imager can accurately collect data under multi-spectral channels. Temperature fields corresponding to the spectral data can be inverted by multi-spectral thermometry method. The temperature results of the multi-spectral thermal imager are compared with that of thermocouples, and the measurement error is<1.5%. According to the experimental data of laser-induced damage field measurements, it is shown that the laser-induced damage temperature field can be acceptably measured with the multi-spectral thermal imager. [ABSTRACT FROM AUTHOR]