Abstract: In order to explore the effect of kind and amount of nitrogen fertilizer on the content of soil inorganic nitrogen and available cadmium, a soil culture experiment was conducted to study the effects of different dosage of urea and ammonium sulphate, calcium nitrate, controlled release urea and dicyandiamide (a kind of nitrification inhibitor, hereinafter referred to as‘DCD’) on change of the content of cadmium and nitrogen in the soil. The results showed that: high N application processing had higher ammonium nitrogen and nitrate nitrogen content, for the different dosage of urea treatment. DCD significantly inhibited nitrification of ammonium sulfate. With coats outside, controlled release urea, slowed down the ammonium nitrogen and nitrate nitrogen transformation trend. With the help of microorganisms, hydrolysis reaction and nitration reaction would happen after the application of nitrogen fertilizer, which made the soil pH change in response. And that change of soil pH made the content of available cadmium get high or low.