Abstract: Taking ‘Italian Resistant-bolting’ lettuce（Lactuca sativa L.） as the material, hydroponics was used as treatment.Different light qualities（red blue light ratio was 4∶1,1∶2 and full red, full blue） and exogenous zinc concentration(0,0.5,1.0 mg·L^-1 ZnSO₄·7 H₂O) were set.The regulation effect of exogenous zinc on the growth and quality characteristics of lettuce in hydroponic culture under different light qualities was stuided, in orer to provide reference for plant factories to apply exogenous zinc under different light quality to improve vegetable yield and quality.The results showed that high proportion of red light could promote the accumulation of biomass, soluble sugar and reducing sugar, and reduce the content of nitrate in lettuce, and the light quality treatment with blue light ratio of 4∶1 had the best effect.High proportion of blue light could promote the increase of photosynthetic pigment and soluble protein, and the full bule light treatment had the best effect, but the full blue light treatment could inhibit the growth of the plant.From the interaction effect of light quality and Zn, light quality played a leading role in the growth and quality of lettuce, while exogenous Zn played a regulating role.In conclusion, root application of 0.5 mg·L^-1 ZnSO₄·7 H₂O with a ratio of red to blue light of 4∶1 had the best promoting effect on growth and development, yield improvement and quality.