Abstract: In order to explore the effect of increasing microbial agents on the growth and quality of spinach under the condition of reducing nitrogen fertilizer application, by using the pot experiment, six nitrogen fertilizer gradients were set up in the soil, and N1 was a constant fertilization treatment (225 kg·hm⁻², equivalent to 103.5 kg·hm⁻² pure nitrogen). Compared with N1 constant fertilization treatment, N2～N5 reduced nitrogen by 20%, 25%, 30% and 35%, respectively. N6 was 100% nitrogen reduction treatment. Under each nitrogen fertilizer level, the water control (CK), SDB5 microbial agent and SDB9 microbial agent were set up, which were combined into 18 treatments. Then, the effects of different treatments on the growth index and nutritional quality of spinach were investigated. The results showed that the leaf number, plant height and aboveground fresh weight of spinach were significantly increased with the application of SDB5 and SDB9 microbial agents at the N4 level. Compared with N4-CK, the number of leaves of N4-SDB5 and N4-SDB9 increased by 30%, the plant height of N4-SDB9 increased by 18.2%, and the aboveground fresh weight of N4-SDB5 increased by 57.5%, reaching 6.3 g. At the N3 level, the improvement effect of SDB9 microbial agent on the nutritional indexes of spinach leaves was better than that of other treatments; while at N4 level, SDB5 microbial agent had better effect on reducing the nitrate content in leaves. Compared with N3-CK, the soluble protein content of spinach leaves in N3-SDB9 increased by 24.2%, the nitrate content decreased by 17.5%, and the oxalic acid content decreased by 48.2%, and the difference was significant. There was no significant difference in soluble sugar and vitamin C content. The nitrate content of N4-SDB5 was significantly lower than that of N4-CK by 46.9%. In summary, reducing nitrogen by 25%～30% and increasing SDB5 and SDB9 microbial agents could promote the growth of spinach to a certain extent and improve the nutritional quality.