A device based on electrolyte cathode atmospheric glow discharge atomic emission spectroscopy(ELCAD-AES) has been developed to determine the metal ion Pb in water.The emission intensity of Pb was significantly enhanced with the increase concentration of Pb,and the emission intensity has a linear relationship with concentration while the concentration of Pb in the range of 10~80 mg·L-1.The effects of discharge current and easily ionizable elements on the emission spectral of Pb were investigated,and the emission intensity reached greatest when the discharge current increased to 70 mA,and the easily ionizable elements generated weak effect on the emission spectral of Pb.The effect of acidification regent on emission spectral of Pb was discussed.It was found that it perform best when acidified with HNO3,and reducing the pH can improve the emission intensity of Pb effectively.The emission intensity of Pb at different region was detected near cathode region,thus obtained the best detection position.Under the optimized experimental parameters,the detection limit of Pb was 0.7 mg·L-1 and relative standard deviation was 1.7%.The recovery of samples was 95%~106%,result and shows that this method has better accuracy.These results provide an available method for further research of detection trace heavy mental elements in water using ELCAD-AES.