A preparation method of a neodymium-graphene composite material, characterized by comprising the steps of: step 1. growing graphene on a nickel foam surface of a substrate by using nickel foam a chemical vapor deposition method with carbon-containing gas as a carbon source to obtain a graphene nickel foam material, the process of growing the graphene on the surface of the nickel foam substrate by using the chemical vapor deposition method to obtain the graphene nickel foam material in the step 1 comprises: placing nickel foam in the tube furnace, introducing a gas mixture of hydrogen and argon, then increasing the temperature to 900-1200°C, and introducing carbon source gas to grow the graphene on the surface of the nickel foam substrate, the time for introducing the carbon source gas is 15-25 minutes, and the flow rate of the carbon source gas is 90-110 sccm, the graphene nickel foam material is placed in a tube furnace, meanwhile the gas mixture of hydrogen and argon is introduced, and the flow rate of the gas mixture is 90-110 sccm, and the nickel foam is cleaned by using ethanol before the nickel foam is placed in the tube furnace; and step 2. preparing neodymium elements on a graphene surface of the graphene nickel foam material to obtain a neodymium-graphene composite material, the preparation of the neodymium elements on the graphene surface of the graphene nickel foam material described in the step 2 specially comprises: placing the graphene nickel foam material in the tube furnace, placing neodymium fluoride powder in the tube furnace, and heating to 1200-1400 °C, so that the neodymium fluoride is volatilized and decomposed to produce neodymium-containing elements, and the neodymium-containing elements are deposited on a surface of the graphene, and the preparation of the neodymium elements on the graphene surface of the graphene nickel foam material described in the step 2 specially comprises: soaking the graphene nickel foam material in a neodymium nitrate or neodymium sulfate solution, taking out the graphene nickel foam material, drying the graphene nickel foam material, and then conducting heat treatment on the graphene nickel foam in inert gas. step 1. growing graphene on a nickel foam surface of a substrate by using nickel foam a chemical vapor deposition method with carbon-containing gas as a carbon source to obtain a graphene nickel foam material, the process of growing the graphene on the surface of the nickel foam substrate by using the chemical vapor deposition method to obtain the graphene nickel foam material in the step 1 comprises: placing nickel foam in the tube furnace, introducing a gas mixture of hydrogen and argon, then increasing the temperature to 900-1200°C, and introducing carbon source gas to grow the graphene on the surface of the nickel foam substrate, the time for introducing the carbon source gas is 15-25 minutes, and the flow rate of the carbon source gas is 90-110 sccm, the graphene nickel foam material is placed in a tube furnace, meanwhile the gas mixture of hydrogen and argon is introduced, and the flow rate of the gas mixture is 90-110 sccm, and the nickel foam is cleaned by using ethanol before the nickel foam is placed in the tube furnace; and step 2. preparing neodymium elements on a graphene surface of the graphene nickel foam material to obtain a neodymium-graphene composite material, the preparation of the neodymium elements on the graphene surface of the graphene nickel foam material described in the step 2 specially comprises: placing the graphene nickel foam material in the tube furnace, placing neodymium fluoride powder in the tube furnace, and heating to 1200-1400 °C, so that the neodymium fluoride is volatilized and decomposed to produce neodymium-containing elements, and the neodymium-containing elements are deposited on a surface of the graphene, and the preparation of the neodymium elements on the graphene surface of the graphene nickel foam material described in the step 2 specially comprises: soaking the graphene nickel foam material in a neodymium nitrate or neodymium sulfate solution, taking out the graphene nickel foam material, drying the graphene nickel foam material, and then conducting heat treatment on the graphene nickel foam in inert gas.