Effects of different illumination times （8， 12 and 16 h·d^-1） of 200 μmol·m^-2·s^-1 red and blue LED lights with photon flux density ratio of 3∶1 on growth and quality of Lactuca sativa var. ramosa Hort. were investigated. The results show that different illumination times of red and blue LED lights have no significant influence on leaf number per plant， plant height， root length per plant and root activity of L. sativa var. ramosa. Leaf area per plant, and fresh and dry weights of above-ground part per plant and whole plant in illumination time of 12 h·d^-1 （T2 group） are significantly higher than those in illumination time of 8 h·d^-1 （T1 group）， but have no significant difference with those in illumination time of 16 h·d^-1 （T3 group）. In general， contents of chlorophyll a， chlorophyll b， and total chlorophyll in leaf in T2 and T3 groups are significantly higher than those in T1 group， while illumination time has no significant influence on carotenoid content in leaf and quality of L. sativa var. ramosa. Contents of soluble sugar and sucrose in leaf in T2 group are relatively high， while contents of soluble protein and vitamin C in leaf in T3 group are relatively high. Illumination time of 12 h·d^-1of 200 μmol·m^-2·s^-1 red and blue LED lights with photon flux density ratio of 3∶1 is recommended for promoting growth of L. sativa var. ramosa in plant factory.