Using the 15-nitrogen (¹⁵N) tracing method, potential of dissimilatory nitrate reduction to ammonium (DNRA) in Typic Hapli-Stagnic Anthrosols andEndogleyic Hapli-Stagnic Anthrosols soils of the Taihu Lake region as affected by tail water from pig rearing was studied. DNRA rates and relative potentials varied in the range of N 0.68 ~ 0.79 mg kg^-1 dry soil d^-1 and 34.61% ~ 44.45%, respectively, in Typic Hapli-Stagnic Anthrosols soli, and in the range of N 1.14 ~ 1.41 mg kg^-1 dry soil d^-1 and 54.24% ~ 106.70%, respectively in Endogleyic Hapli-Stagnic Anthrosols soil. Irrigation with tail water from pig rearing had little effect on DNRA rates in both soils and DNRA relative potential inTypic Hapli-Stagnic Anthrosolssoil, while it obviously reduced DNRA relative potential in Endogleyic Hapli-Stagnic Anthrosols soil. Correlation analysis indicates that soil DNRA relative potential was significantly positively correlated with the ratio of soil dissolved organic carbon to nitrate nitrogen (DOC / NO₃^-1 -N) at the start (r = 0.836，p< 0.05，n = 6) and the end (r = 0.936，p < 0.01，n = 6) of the incubation, but not significantly correlated with soil Eh or DOC at the start and the end of the incubation. The results indicate that Endogleyic Hapli-Stagnic Anthrosols soil is of much higher DRNA potential, therefore, in practice, it might be possible to enhance N retention through regulation of DNRA and hence to minimize N loss from paddy fields; and irrigation of the soils with tail water affects the contribution of DNRA to dissimilatory NO₃^-1 reduction mainly by changing soil DOC / NO₃^-1 -N and its effect varies with the soil types.