Abstract: In order to assess the effects of acetochlor on transformation of urea nitrogen in soil at different nitrogen fertilizer application rates. An incubation experiment was conducted under laboratory conditions with 7 treatments including nitrogen (0, 75, 150 and 300 mg/kg), nitrogen (75, 150 and 300 mg/kg) plus acetochlor (10 mg/kg, active ingredient). The results showed that, acetochlor had no significantly effect on soil urea hydrolysis and nitrification at 75 mg/kg nitrogen concentration treatments. However, significant negative effect on soil urea hydrolysis was observed at 150 and 300 mg/kg nitrogen concentration treatments (P P < 0.01). This study demonstrated that acetochlor markedly affected the nitrogen transformation in soil. However, under different nitrogen fertilizer application rates, different impacts on the processes of nitrogen transformation were detected.