Abstract: In order to introduce effect of the light emitting diodes (LED) light system on growth and chlorophyll content of spinach, hardware and software of the flexible controlled LED light system were designed. The growth test of spinach under six different light quality LED and set fluorescence lamp as control was carried out. The result showed that light quality, light intensity, photoperiod and duty cycle the LED light system could be flexible controlled and were good light system for supplement light or researches of photobiology. The result of growth experiment in spinach under the light treatments showed that petiole length, leaf area, petiole and root length of the red, blue and yellow (RBY) LED treatment were significantly greater than those of other treatments, and more robust. Furthermore, photosynthetic pigment content of the RBY treatment was significantly higher than other treatments. Supplement yellow light on the basis of the red and blue composite light was benefit to synthesize photosynthetic pigments and significantly promote the growth of spinach.