Based on the study of traditional techniques measuring the spectrum characteristic of light sources and light detectors,through the use of pyroelectric detector,monochromator with auto scanner,lock in amplifier and virtual instrument technique,a new type of spectrum auto measuring system was generated.the measuring range of spectrum characteristics has been broadened,the level of automation has been raised,and the adaptability has been enhanced.Being integrated with LabVIEW,the system has been provided with powerful function for data acquisition and processing,and can offer the user with ample space for further system optimization.