A facile visible-light-assisted method has been demonstrated to synthesize palladium (Pd) nanoparticles (NPs) with single-crystalline and multiple-twinned structures by reduction of PdCl2. The results showed that the formation of different nanostructures depend on reduction rate of the control. Unlike multiple-twinned Pd NPs, single-crystalline Pd NPs exhibit surface plasmon resonance (SPR) peaks in the visible region. Electrochemical properties of Pd NPs have been also investigated by cyclic voltammetry (CV). By comparison of the electrochemical parameters in the oxidation process of Pd NPs with single-crystalline and multiple-twinned structures, multiple-twinned Pd NPs exhibit the better electrocatalytic activity and anti-poisoning capability for ethanol oxidation.