In order to improve the detection sensitivity of laser-induced breakdown spectroscopy (LIBS) and lower the limit of the detection of elements, LIBS combined with Aluminum electrode enrichment method is adopted to analyze heavy metals such as Pb,Cdand Ni in the water. The relationship between the characteristic spectral intensity and the key parameters-voltage of electrode method is discussed, the spectral intensity increases first and then decreases with the increase of voltage. The spectral intensity reaches the maximum value when the enrichment voltage is 1.2 V while the optimal enrichment voltage value is 1.2 V. The stability of characteristic spectral lines of heavy metals is studied, and the relative standard deviation(RSD) of spectral intensity of Pb, Cd and Ni is 5.98％, 4.25 ％ and 5.27％ respectively, the result shows that the spectral line obtained by this method has high stability. A series of samples in the range of 0~0.13 mg·L-1 are prepared and quantitatively analyzed, the limit of detection of Pb, Cd and Ni is obtained 1.2, 3.1 and 1.7 ppb respectively. The above result shows that LIBS combined with aluminum electrode enrichment method can effectively improve the stability of characteristic spectral lines and lower the limit of detection of Pb,Cd and Ni. This research also provides a method to further improve detection sensitivity of LIBS and analysis ability of heavy metal in the water.