It is necessary to monitor heavy metal ions efficiently because they are major sources of environmental pollution. In this paper, a surface plasmatic resonance (SPR) sensor is designed to detect the concentration of heavy metal ions based on the change of refractive index. The theoretical research shows the refractive index is linearly related to the concentrations of solutions including heavy metal ion solution. In this paper, a gold nanoparticles array SPR sensor was simulated to detect the change of refractive index. It is also known that interval and radius of nanoparticles influence the SPR peak. Monitor the change of SPR spectra in aqueous solution. The results demonstrate gold nanoparticles array SPR can detect the concentrations of solutions. This method provides a feasible direction for detecting the heavy metal ions.