The invention relates to a synthetic method of a graphene-waterborne epoxy high-dispersion system. The method comprises steps as follows: step 1, glycidyl ether type epoxy resin and double-end amino micromolecular amine are subjected to an addition chain extension reaction, and an amino-terminated hydrophilic polyether chain segment is obtained; step 2, the amino-terminated hydrophilic polyether chain segment and a macromolecular epoxy group are subjected to an addition chain extension reaction, and an amino-terminated long-chain non-ionic self-emulsifying epoxy curing agent is obtained; step 3, low-oxidation graphene is prepared with an ultrasonic assisted Hummers method; step 4, the non-ionic self-emulsifying epoxy curing agent and low-oxidation graphene are subjected to a covalent grafting modification reaction, and the graphene-waterborne epoxy high-dispersion system is obtained. The synthetic method has the advantages as follows: the long-chain non-inoic self-emulsifying epoxy curing agent is grafted on the surface of graphene through a nucleophilic opening ring reaction, re-agglomeration of a graphene sheet layer is inhibited to a certain extent, the electric conductivity of graphene is retained, and the comprehensive mechanical performance and modulus of the graphene-waterborne epoxy high-dispersion system are improved effectively.