We prepared polystyrene (PS)/silver (Ag) core-shell particles with an excellent electrical conductivity in a facile, affordable and eco-friendly way. As core particles, monodisperse PS particles were synthesized by the process of dispersion polymerization. Then, the PS particles were coated with polydopamine (PDA) through the spontaneous oxidative polymerization of dopamine to produce PDA-coated PS particles. In essence, it is noted that the catechol and amine groups of PDA coated on PS particles can weakly reduce metallic ions. As a secondary reducing agent with an affordable price, glucose was therefore added to promote the reduction of metallic ions. Herein, the effect of glucose concentration on the Ag shell thickness of PDA-assisted PS/Ag core-shell particles was investigated. The degree of Ag reduction increased with an increase characteristically in glucose concentration, resulting in the increase of Ag shell thickness. Notably, a thick and uniform Ag shell layer could be plated on PDA-coated PS particles, which were noted to have rendered excellent electrical conductivity. When the glucose concentration of 55 mM was applied, the electrical conductivity of the PS/Ag core-shell particles reached as high as 7.8×105 S/m, which was almost close to that of conductive metals.