1, 5-Diphenylcarbohydrazide spectrophotometric method has been applied in determining chromium (Ⅵ) in environmental water with suitable solid solubilizer and solid acid. The complex has a maximum absorption at 540 nm and an apparent molar absorptivity of 4.06×10⁴ L/(mol﹒cm). Beer’s lawis obeyed in the range of 0～0.5 mg/L for chromium (Ⅵ). The familiar concomitant ions will not disturb the determination. The mixed reagent has a long period of validity. The method is accurate, sensitive, rapid and simple for the determination of chromium(Ⅵ).