It is composed of C-T monochromator with grating dspersion, servo motor for high speed wavelength position, and high sensitive PMT. It coudl be widely used in fast measurement of spectrum, photometry and chromaticity. It could obviously reduce the effect of the light source, and also save the test time. Meanwhile, it could be used to analyze the flash run-up characterstics of light sources, warm-rup time and spectrum of the starting time. It is suitable for research of the discharge and lifetime for light source starting.