Under alkaline conditions,Fluorescein mercury has strong fluorescence,however,when it met S2-,its fluorescence would quench,in view of the above,a fluorescence method for determination of H2S in biological samples was established.In the 0.1 mol·L-1 NaOH dilution,when the concentration of fluorescein Mercury and Na2S was 5.0×10-5 and 1.0×10-5 mol·L-1 respectively,the fluorescence intensity of system was determined at 522 nm.The results showed that,at the range of 4.0×10-7~2.0×10-6 mol·L-1,the concentration decreasing of H2S and fluorescence intensity had good linear relationship,r=0.998 0,the RSD of precision test was 4.59% (n=7),the detection limit was 3.5×10-8 mol·L-1,the content of H2S in the sample were 1.01×10-6 and 1.15×10-6 mol·L-1,and the recovery rate was 95.8%~101.0%,the method has the advantages of simple operation,high sensitivity,good selectivity,can accurately determine of H2S in intestinal perfused solution,and provides the basis for the determination of endogenous H2S.