In this research the development of the conditions of the determine copper duo by spectrophotometric method that based on the formation of a complex with Alizarin Red S was accamplished with the presence of fallow acid when the wavelength(220 nm), that by studying the effect of PH and the impact if the interference caused by the presence of some metal ions (nickel ions, chromiun ions, 2 inc ions, calciom ions, and triple iron ions) which make it difficult for the progress of determine copper by Alizarin Red S. the best PH value for this process is (pH = 9.5) and the relationship of Lambert Bear realized within the range 0.2 – 125 mg/ml the detection limit was 0.OO1µg/ml.