Abstract: In this paper a method for the determination of nitrate in nitratite samples by oxidationreduction tritimetry with ammonium ferrous sulfate was developed. The samples were dissolved with HCl and nitrate was reduced to NO by ammonium ferrous sulfate, then potassium dichromate was used to titrate excessive Fe2+. The dose of HCl and heating time of sample solution were optimized. The method has been applied to the determination of nitrate in practical samples with precision of 0.73%~2.00% RSD (n=8). The recovery of the method is 99.0%~101.0%. The results show that the method is suitable for the determination of nitrate in nitratite ores with >1% of nitrate.