A new chromogenic reagent 2-（2-quinolylazo）-5-Dimthylaminophenol（QADMAP）was synthesized,and its structure was verified by elemental analysis,infrared spectrum,（）1H nuclear magnetric resonance spectrum,and mass spectrum.The color reaction of QADMAP with uranium was studied.In the presence of pH=7.8 buffer solution,when fluorin ion and TritonX-100 medium existed,QADMAP can react with uranium and fluorin to form a stable 1∶1∶1 purple complex（F∶QADMAP∶U（VI））.The molar absorptivity is 1.12×105L·mol-1·cm-1 at 590 nm.Beer’s law is obeyed in range of 0～50 μg/25ml.This method was applied to the determination of uranium in ore with good results.
