Abstarct: In the first section of this thesis three novel spectrometric methods including extended ratio subtraction method (EXRSM) Constant center coupled withspectrum subtraction (CC-SS) Ratio H-point standard addition method (RHPSAM) were presented for simultaneous determination of m-Nitroaniline and o-Nitroaniline .In the second section, same methods were considered for simultaneous determination of p-Nitroaniline and o-Nitroaniline. effective factors on sensitivity of method were considered and optimised. In the first section of this thesis, for the three methods used, Linear range of 5-40 and 5-25 mg.L-1 were respectively obtained for m-Nitroaniline and o-Nitroaniline, However, the Linear range were 0.5-10 and 2-20 mg.L-1 respectively for p-Nitroaniline and o-Nitroaniline using the three methods in the secend part of research. In the first section, using EXRSM, CC-SS and RHPSAM methods, the detection limit for m-Nitroaniline were respectively 0.320, 0.030, 0.480 mg.L-1 and the detection limit for o-Nitroaniline were respectively 0.09, 0.09 and 0.1 mg.L-1. In the secend section, the detection limit for p-Nitroaniline were 0.160, 0.023 and0.56 mg.L-1 and for o-Nitroaniline were 0.120, 0.090 and .083 mg.L-1, respectively for EXRSM, CC-SS and RHPSAM methods. the Influence of diffrent interferences on the selectivity of the methods were also considered. All proposed methods have admissible precision and accuracy for determination of m-Nitroaniline, p-Nitroaniline and o-Nitroaniline in their binary mixtures exist in tap water.