The invention provides a preparation method of a catalyst of porous graphene loading precious metal nano particles. The method is as follows: bamboo and pine dust powder or leftover material and the like are calcined at high temperature in anoxic atmosphere, then immersed into a precious metal ion- containing solution, maintained for 1 ~ 1000 minutes, then taken out, then calcined at high temperature in anoxic atmosphere, and immersed into a strong oxidizing solution, so that the bamboo charcoal or charcoal graphite structure is fully oxidized into graphite oxide; then the graphite oxide is taken out and placed in anoxic atmosphere for calcination for 0.01 ~ 0.5 hour at the high temperature of 500 to 1000 DEG C. The graphene prepared by the method is in a porous structure, has good water permeability and air permeability characteristics, can meet fast mass transfer requirement required by electrode reaction; precious metal nanoparticles are firmly attached to the inner wall of graphene channels to react with transferred-in water, gas and electrons to form numerous micro three-phase reaction zones, the reaction activity area is greatly increased, and the catalyst has excellent catalytic reaction activity.