Abstract: A variety of monochromatic light generator was introduced, which could produce photosynthetically active radiation by double hump spectral light source．The equipment was developed on the basis of principle of plant photosynthesis and invention patent of an experimental method of plant characteristic spectrum．Plant characteristic spectrum test system was composed of monochromatic light device and the photosynthesizer．Photosynthetic response curves of different monochromatic light could be measured by plant characteristic spectrum test system, and corresponding light saturation point and light compensation point, saturation point curve and compensation point curve could be obtained．At the same time, specific case application of the system was introduced, aiming at providing technical guidance for plant lighting．