Three soils with different pH values were obatined from an acid soil by adding NaOH. The relationship between the changes of soil pH and N2O production from soils in the NH4+ oxidation progress was studied. The results showed with the increase of soil pH nitrification activity and the amount of N2O production increased while the contribution of pure chemical reaction to N2O emission from soil decreased. The results also showed that nitrapyrin can inhibit the nitrification in soil with pH 4.8 and pH 6.0, whereas there was no obvious inhibiting effect at soil pH 8.5 and nitrapyrin enhanced the emission of N2O in the incubation.