Abstract: The combination of appropriate chosen red and blue LED could be a kind of light source which is similar as the absorption peak of light spectrum of plant photosynthesis and morphogenesis. It is significant to make sure the uniform distribution of irradiation of the light source. Two combinations of array were designed through the point light source model. Array 1: The proportion of red LED and blue LED was 1∶1， the array was evenly spaced. Array 2: the proportion of red LED and blue LED was 4∶1， every four red LED took the four corners of the square， and one blue LED took the center. The calculation and simulation of the TracePro software showed that: the uniformity of array 2 was better than array 1. The array 2 was progressed as follow: increase the distance of the LED array. With this progress， the uniformity of the proportion of R/B in its radiate area increased， which was beneficial for the weld of circuit board and overall heat dissipation of LED array. In order to meet the needs of supplementary lighting of plants， intensity of light was controlled through changing the working current. Modularized design could make the install， exchange and expandability rapid， and keep the uniformity of the light in the radiated area.

Key words: plant light supplement, LED, assembled light source, illumination uniformity of radiation intensity