A homemade experimental setup of laser-induced breakdown spectroscopy (LIBS) with aqueous jets was used to compare the detection results of dual-pulse (DP-LIBS) and single-pulse laser-induced breakdown spectroscopy (SP-LIBS) for heavy metal elements in liquids. Two Q-switched Nd∶YAG lasers that operated at 532 nm were utilized to generate plasma on the AlCl3 aqueous jets. The plasma emission signal was detected by spectrometer with an intensified charge-coupled device (ICCD). The effects of laser-pulse energy, ICCD gate width, and ICCD gate delay on the intensity of the Al spectral line at 396.15 nm were presented for SP-LIBS. Experimental results showed the optimum parameters for laser energy, ICCD gate width, and gate delay were 50 mJ, 150 ns, 1 200 ns, respectively. The influence of experimental parameters, including interpulse delay, total pulse energy, and ICCD gate delay on the signal enhancement of the Al 396.15 nm spectral line intensity was investigated and optimized. Results showed that the optimal parameters for interpulse delay, total pulse energy, and ICCD gate delay were 1 000 ns, 50 mJ, 1 100 ns respectively. The detection limits of Al were 26.79 and 10.80 ppm by SP-LIBS and DP-LIBS, respectively. The results indicated that DP-LIBS can improve the detection sensitivity which offers a feasible basis for the detection of metallic elements in liquid.