In order to investigate the effects of syringic acid (SA), a biological nitrification inhibitor (BNI), on soil nitrification and nitrous oxide (N₂O) emissions in different soils, three typical agricultural soilsnamely calcareous soil, paddy soil, and yellow soil, were selected for incubation experiments. The effects of different SA concentrations on nitrification rate and N₂O production in the three soils were studied, and the main factors regulating the effect of SA were explored. The results showed that SA had inhibitory effects on soil nitrification and N₂O emissions in neutral paddy soil and acidic yellow soil, with inhibition rates of 20% to 55% and 11% to 60% on soil nitrification rate, and inhibition rates of 55% to 65% and 13% to 24% on soil N₂O emissions, respectively. On alkaline soil, SA had no significant effect on soil nitrification rate and N₂O emissions. The inhibition of soil nitrification by SA on yellow soil had a dose effect, while such a dose effect was not found on the reduction of N₂O emissions. Two factor analysis of variance showed that both soil type and SA concentration affected nitrification inhibition efficiency of SA, and they had an interactive effect, but the latter had no significant impact on emission reduction of soil N₂O. The correlation heatmap analysis further indicated that soil pH, organic matter and clay content may be key factors affecting soil nitrification inhibition and N₂O emission reduction of SA. In conclusion, soil conditions with slightly acidity, high organic matter and clay content are more conducive to the effectiveness of SA, which provides a theoretical basis for the precise application of BNIs.