Based Plank’s radiation law, thermal radiation intensity depends on radiation wavelength and material temperature. As the increase of material temperature, thermal radiation wavelength will decrease from infrared waves, next to visible light, last to ultraviolet light. In order to research the spectral distribution of molten pool at different temperature in laser fabricating, thermal radiation of standard BF1400 blackbody furnace in National Institute of Metrology of China was measured by CCD technique. Its high-temperature cavity radiators glow which was dim red at 600 oC, bright red at 800 oC, yellowish red at 1000 oC, bright yellow at 1200 oC. The thermal radiation in visible spectrum range could be acquired by CCD, which was translated into grey data of red, green and blue radiation intensity. It was shown that grey gain at red, green and blue wavelength was different greatly as increase of blackbody temperature, extremely large at red wavelength, little at blue and green wavelength. When thermal radiation of molten metal pool at red, green and blue wavelength in laser fabricating was acquired to analyze the relation between spectrum and temperature, the green and blue wavelength will be good choose for its colorimetry temperature analysis.