Surface Plasmon resonance (SPR) based heavy metal ions sensor is one of the most sensitive sensor for detecting toxic metal ions. It is an inexpensive, portable and also feasible for real time detection. SPR sensor is a type of optical sensor in which toxic metal ions get adsorbed on the functionalized metal (mostly Au) film causes the change in refractive index of the metal (Au)-dielectric (sensing) medium. The change of the refractive index leads to a shift in the angular spectrum of the reflected light and can be accurately monitored by optical methods. In this paper,we are trying to optimize the detection level of heavy metal ions by surface plasmon resonance on gold nanoparticles using UV-VIS spectroscopy. Polymer like chitosan is being used with gold nanoparticles to detect copper and zinc ions and detection till very low concentrations of the toxic metal ions is obtained. Keywords: Surface Plasmon Resonance, Optical sensor, metal nanoparticles, reducing agent,chelating agent, polymer capping. *Cite as: Sandhya Banti Dutta Borah, Sunandan Baruah, Waleed Soliman & Joydeep Dutta “Heavy Metal Ion Sensing By Surface Plasmon Resonance On Gold Nanoparticles” ADBU-J.Engg Tech, 1(2014) 0011404(5pp)