Tomato plants were planted in rock wool in an artificial light plant factory and exposed to red background light with supplementary or substituted blue light. The nutrient element absorption by tomato plants and the spectral parameters of tomato leaves were analyzed. The results showed that compared with constant pure red light, both supplementary and substituted blue light decreased the content of K in tomato leaves but increased that in tomato stems, interventional blue light might inhibit the transport of K from stems to leaves;both supplementary and substituted blue light increased the content of Mg in the whole tomato plant by 8.93%~13.63% while decreased that of Fe by 28%~48% and Mn by 3.93%~21.24%. Among which, Mg content in tomato leaves was increased with the increase of supplemental blue light intensity. The content of Mg was higher in tomato plants treated with substituted blue light than that treated with supplementary blue light, while Fe content showed opposite trend. Substituted blue light seemed more conducive to the accumulation of Mg in tomato leaves as well as the inhibition of Fe in the whole plant. Compared with pure red light, the Hue and MCARI value of tomato leaves treated with interventional blue light was increased, while the Red/Green value was decreased;Hue and MCARI value was increased with the increase of supplemental blue light intensity. Hue and MCARI value were the highest under R/RB80 treatment, which were respectively 4% and 124% higher than the control. In substituted blue light mode, Hue and MCARI value first increased and then decreased with the prolongation of blue light intermittent time, reaching the highest values under R/RB(1h) treatment, which were 6% and 215% higher than the control respectively. The reflectance of tomato leaves in the green light area was close to the change trend of Hue and MCARI value among treatments, while Mg content in tomato leaves showed a certain positive correlation with chlorophyll spectral parameters. Comparing with the spectral parameters of tomato leaves under the two modes of interventional blue light, it can be seen that substituted blue light was more conducive for the decomposition of carotenoid and the accumulation of chlorophyll in leaves than supplemental blue light on the basis of equal total light amount. The discontinuous light supply mode might regulate the absorption of inorganic elements in tomato plants, thereby affecting the formation of leaf pigments. The research result can provide some theoretical basis for the regulation of light environment in soilless tomato cultivation.