A novel three-dimensional graphene surface-mounted nickel-based metal organic framework (3D Gr/Ni-MOF) electrocatalyst was fabricated via freeze-drying technique and ultrasonic assisted method. The morphology, elemental composition, crystal structure, functional group structure, specific surface area and pore size of the composite were analyzed by SEM, EDS, XRD, FTIR, and BET. A series of conditional experiments from the aspects of organic ligand screening, ultrasonic time, molar ratio of metal salt to ligand, and porous graphene loading were carried out to optimize 3D Gr/Ni-MOF composite. Oxygen Evolution Reaction (OER) catalytic performance, OER process kinetics, stability and the deeper causes of enhanced OER performances of 3D Gr/Ni-MOF were also investigated via a group of electrochemical methods. The experiment results showed that 3D Gr/Ni-MOF composite prepared with 2,5-pyridinedicarboxylic acid as ligand, 1:1 M ratio of nickel acetate to ligand, 10 mg of 3D Gr loading and 8 h of ultrasonic process exhibited the most excellent OER activity. Its overpotential of 370 mV was much smaller than rGO/Ni-MOF, Ni-MOF and 3D Gr prepared under the same conditions, and as non-precious metal catalyst, it has the traits of low cost, easy preparation, high activity and durable stability. (C) 2019 Elsevier Ltd. All rights reserved.