The radiation temperature measurement system was constructed by color camera and multispectral camera. The blackbody furnace was used to conduct the temperature calibration experiment, and the calibration data were used to obtain a temperature measurement model based on BP neural networks. The reliability of the temperature measurement model was verified by the temperature measurement experiment of a candle flame, and the results showed that the accuracy of the multispectral imaging temperature measurement system was higher than the color camera temperature measurement system. For the problem of insufficient spatial resolution of conventional radiometric temperature measurement system, a microscopic temperature measurement system was established using a hot stage microscope (HSM) and a multispectral imaging camera. The combustion process of single petroleum coke particles inside the high-temperature hot stage was recorded. The temperature distribution on the surface of petroleum coke particles and the temperature change process with time were obtained.