The results showed that supplying nitrogen fertilizer could increase the nitrate accumulation in rape sharply, and Rape’s nitrate accumulation increased with fertilization increasing. According to ether of the two Nitrogen Fertilizer rates: supplying Rape with Ammonium nitrate, rape’s Nitrate Reductase Activity (NRA) was restrained strongly, so rape’s nitrate accumulation was very high; while supplying Rape with Urea, rape’s nitrate accumulation was comparatively low because their NRA was comparatively strong. When Rape supplied with Calcium nitrate, though nitrogen fertilizer provided was in form of NO3- totally and rape’s NRA was not strong enough, its nitrate accumulation was lower than that with the supplying of Ammonium nitrate because of the influence of Calcium. If Ammonium Sulfate supplied, when the supplying rate was lower, Rape’s nitrate accumulation was lower than any one of the rest lower nitrogen treatments ; while the rate was higher, its nitrate accumulation was comparatively high.