A method for polarographic determination of nitrites in water is developed. Nitrites firstly react with resorcinol, then the nitroso product reacts with nickel ion to form a complex, which can be reduced on dropping mercury electrode to produce a sensitive polarographic wave. The current signal has an excellent linear relation with the concentration of nitrite, the detection limit was 0.22 μg/L. The relative standard deviation is 2.80% and the recoveries were 95.0–102.9% at a nitrite concentration of 1.13 μg/L, most of the potential interferents are tolerated. The method is suitable for the determination of trace nitrite in water.