Abstract: A transient-imaging multi-spectral temperature-measurement system was developed to measure the surface temperature of high-temperature hot-end components in the aerospace field. The application of this system was investigated, included the four-quadrant operational principle, system structure, and algorithms for nonuniformity correction, radiation calibration, and multispectral radiative temperature measurement. First, the measurement principle and optical–mechanical system structure of the quad-slice device were elaborated and analyzed. Next, the design and development of quantification and processing techniques for the multispectral data used in field temperature calculations were conducted. These included techniques for non-uniformity correction, radiometric calibration, and SVD-based multispectral radiative temperature measurement. Finally, non-uniformity correction and radiometric calibration experiments were conducted using an integrating sphere light source and a standard blackbody radiation source as calibration standards. Experiments were conducted in which the surface temperature of a graphite sample was measure using a colorimeter thermometer and Telops thermal imager as temperature standards. The experimental results indicated that the quantification and processing algorithms for the multispectral data could significantly improve the detection accuracy of transient-imaging multispectral temperature-measurement systems. The temperature measurement accuracy of the system was within ±1% in the range of 600–2100 ℃. It could satisfy the stability, reliability, and accuracy requirements when measuring the surface temperatures of high-temperature hot-end components in the aerospace field.