In this work, the laser induced breakdown spectroscopy(LIBS) technique, which combined with the sample treatment method of liquid-solid conversion on zinc substrate, was used to detect the Fe and Mn in standard aqueous solution samples, and the quantitative models of Fe and Mn were established according to the standard curve method. The contents of Fe and Mn in groundwater from Dongting Lake area were detected by LIBS quantitative model, and the results were compared with those obtained by inductively coupled plasma mass spectrometry(ICP-MS). The results showed that the determination coefficients of LIBS calibration curves of Fe and Mn were greater than 0.98, and the relative standard deviations were 4.3%. The root-mean-square errors of cross-validation were 0.024 and 0.007 mg/L, and the detection limits of Fe and Mn were 0.028 and 0.008 mg/L, respectively. The average relative error was less than 10% when LIBS was used to detect Fe and Mn in comparison with the ICP-MS.