NOVELTY - A graphene supported two-dimensional branched nanometer molybdenum electrocatalyst preparing method involves dissolving phospholipid and cholesterol in chloroform to obtain dissolved solution. The solution is rotary evaporated to obtain multilamellar liposomes membrane, followed by adding reducing agent aqueous solution to the membrane. The membrane is heated and extruded to obtain a porous membrane. The porous membrane is dispersed in a reducing agent, and added with graphene and with water-soluble molybdenum salts and dispersed to obtain solid product. The solid product is washed and dried.    USE - Method for preparing a graphene supported two-dimensional branched nanometer molybdenum electrocatalyst that is utilized in proton exchange membrane fuel cells (claimed).    ADVANTAGE - The method enables preparing the graphene supported two-dimensional branched nanometer molybdenum electrocatalyst with mild condition, in a simple, easy and environmental friendly manner.    DETAILED DESCRIPTION - A graphene supported two-dimensional branched nanometer molybdenum electrocatalyst preparing method involves dissolving phospholipid and cholesterol in chloroform to obtain dissolved solution. The solution is rotary evaporated to obtain multilamellar liposomes membrane, followed by adding reducing agent aqueous solution to the membrane. The membrane is heated at 40-80 degrees C for 10 minutes and extruded to obtain a porous membrane. The porous membrane is dispersed in an aqueous solution of unilamellar liposomes reducing agent to obtain mixture. The mixture is added with graphene and with water-soluble molybdenum salts and dispersed at 0-100 degrees C for 30 minutes to obtain solid product. The solid product is washed with water and an organic solvent, and dried to obtain a finished product, where the molar ratio of the phospholipid to cholesterol is 1/5-50/1, and the molar ratio of the reducing agent and water-soluble molybdenum salts is 1/1-50/1. An INDEPENDENT CLAIM is also included for a graphene supported two-dimensional branched nanometer molybdenum electrocatalyst comprising two-dimensional branched nanometer molybdenum sheet that supported on grapheme, where the two-dimensional branched nanometer molybdenum sheet has thickness of 2-3 nm.