A phenanthroline based fluorescent probe 1 was synthesized.The structure of the probe was characterized by nuclear magnetic resonance spectroscopy(NMR),masss pectrometry(MS) and infrared spectroscopy(IR),and the recognition performance of the probe toward Hg2+ and Ag+ was investigated by fluorescence emission spectroscopy.Results indicated that Hg2+ and Ag+ in pure water medium were recognized by the probe via fluorescence quenching with the ratios of 1∶1 and 2∶1,respectively.There were linear relationships for Hg2+ and Ag+ in the concentration ranges of 9.0×10-7-1.1×10-5mol/L and 8.0×10-7-7.0×10-6mol/L,respectively,with their correlation coefficients(r2) larger than 0.99.The limits of detection were both as low as 10-8 mol/L.A visual analysis method was established for the detection of trace Hg2+ and Ag+ using the probe based on the obvious changes of fluorescence intensity.The thermodynamic parameters and recognition mechanism were evaluated using isothermal titration calorimetry(ITC) and 1H NMR titration.This method has a potential application value for the real-time monitoring of Hg2+ and Ag+ in the biological and environmental fields.