Abstract: This study aimed to explore the effect of Light quality on the growth and vitality of peanut root system based on indoor monochromatic light. The results showed that, compared with Natural light, Red light (610-660nm) could promote the growth and development of peanut seedling root system significantly, much longer main and lateral root length, more lateral root numbers, more dry matter accumulation, stronger root vitality; Blue light (445-470nm) had significant inhibition on the growth of root system, less root distribution range, but stronger root vitality; Yellow light (590-595nm) and Green light (515-520nm) could inhibit the growth of peanut seedling root system and lower root vitality.