PtPd/SnO2 nanocatalysts were synthesized by a simple one-step way of plasma technique in an aqueous solution of tin(II) chloride by using Pt and Pd metal wire as the electrode pair. PtPd/SnO2/GNs composite catalysts were prepared by an ultrasonic mixing PtPd/SnO2 with GNs (GNs, graphene nanosheets). The PtPd/SnO2/GNs composite catalysts exhibit a significantly enhanced electrocatalytic performance, cycling stability and CO-poisoning tolerance towards methanol oxidation both under acidic and alkaline condition, which attributed to the synergism of PtPd alloy and SnO2. What's more, the current density of PtPd/SnO2/GNs composite catalyst was obviously improved under light illumination, with 10,029 mA mg(Pt)(-1) which was about 1.3 times higher than that without light illumination under alkaline condition. The novel one-step plasma technique could provide a useful approach for fabricating other highly efficient electrocatalysts.