The four spinach varieties with significant differences in the content of nitrate under nutrient solution culture were used as materials. The growth indexes(plant height, root length, plant width, stem length, dry weight, fresh weight and leaf area), photosynthetic pigments(chlorophyll a, B and carotenoid), photosynthetic parameters(Yield,ETR,qP and qN), nitrate uptake rate and nitrate reductase activity were determined, and the physiological differences of different genotypes were studied. The results showed that: （1）The nitrate content of spinach leaves with different genotype materials is always different, and there is no significant correlation between nitrate content and biomass. Under the same cultivation conditions, the varieties with large biomass does not mean that the nitrate content is low.（2）The spinach with high nitrate content were lower in photosynthetic pigments, photosynthesis, and nitrate reductase activity; and higher in nitrate uptake rate. The spinach with low nitrate content had higher photosynthetic pigment content, photosynthesis and nitrate reductase activity; and nitrate uptake rate were lower. （3）Among them, the comprehensive evaluation of the low nitrate content genotype SL0613 was the best, which could be used as the material for the selective breeding of spinach cultivars with low nitrate content. In conclusion, the difference of nitrate content in different spinach genotypes is probably due to the effect of nitrate uptake and transport.