While solid sample analysis by LIBS is more easy and straightforward, liquid analysis is more troubling. One of the studies aimed at removing the problems in liquid analysis is the Nanoparticle Enhanced LIBS technique. This study aims to investigate the effect of the presence of Ag nanoparticles of different shape and absorption wavelengths on the signal strength of heavy metals Pb and Cr. For that purpose, spherical, prism, and disc-shaped silver nanoparticles with an absorption wavelength in the range of 394-761 nm were used. Among all types of NPs with different sizes and shapes, silver nanoparticles with an absorption maximum at 535 nm were found to enhance LIBS signal intensity of Pb element at 405.8 nm 5-6 times, and that of Cr at 428.9 nm 3-3.5 times. Under optimized conditions, a LOD value of 1,16 and 0.69 ppb were obtained for Pb and Cr, respectively. The applicability of the system for the determination of Pb and Cr in aqueous environments has also been tested on reference water samples. The silver nanoparticle with an maximum absorbance wavelength of 535 nm shows the most improvement in signal. The wavelength of the laser used is very close to the absorbance wavelength of the silver nanoparticle, effectively overlapping it. Thanks to the transmitted laser light, plasmons are formed on the nanoparticle surface. These formed surface plasmons interact with the laser electromagnetic field, resulting in an increase in the signal.