Heavy metal contamination in water solution is increasing, requiring a simple and fast detection method. Laser-induced breakdown spectroscopy (LIBS) technology meets these needs. Applying LIBS to detect heavy metals in water solution faces problems such as the contamination of optical devices for liquid splashing and plasma quenching. Without preconcentration, in the experiment, the lead (Pb) detection sensitivity in water solution is improved by using thin laminar flowing, spatial confinement and adjusting water flowing speed, which has the characteristics of simple device and fast detection. LIBS technology is used to detect heavy metals in water solution, by optimizing experimental parameters such as characteristic spectral line, laser energy and delay time, the spectral line intensity is eventually increased by four times, which has a high application value.