Abstract: A new ultrasensitive and selective method based on the ionic associated complex in the system of uranium(Ⅵ)-thiocyanate-ethyl violet-polyvinyl alcohol is investigated. The complex gives maximum absorbance at 550 nm in a solution containing 0.36-0.48mol/l sulfuric acid. Its apparent molar absorptivity in 5.8×106l- mol-1@cm-1. Beer's law is obeyed for uranium(Ⅵ) in the range of 0 to 2.5 ng/25ml.Tolerance limits are determined for various foreign ions. This method has been applied to rapid and direct determination of trace amounts of uranium(Ⅵ) in ores and minerals with satisfactory results.