Abstract: In recent years, diamond-graphite composite film has become a research hotspot for field emission cathode materials due to its high vertical ratio and high electrical conductivity, as well as high mechanical hardness and chemical inertness. This paper breaks through the limitations of the microstructural regulation performance of traditional field emission cathode materials, regulates the electronic structure of composite films with metal nickel, adopts microwave plasma chemical vapor deposition (MPCVD) method, introduces metal nickel sources synchronously during the growth process, and prepares a nickel-containing diamond-graphite composite film, which does not contain metal nickel composite film, after the introduction of metallic nickel, the field emission performance of the composite film is reduced to 1.7 V/μm, and the current density under the 4 V/μm electric field reaches 9.23 mA/cm². Research shows that the introduction of metal nickel into a diamond-graphite composite film can regulate its electronic structure, that is, reduce the surface function and strengthen the transport of electrons in the film, so as to significantly reduce the field emission opening field strength and improve the emission current density. This paper studies to obtain a new field emission with low opening field strength and high emission current density. The cathode material provides new ideas.