The invention discloses a GaAs nano optical resonance structure photoelectric negative electrode electron source, and belongs to the technical field of photoelectric negative electrodes; the structureof the photoelectric negative electrode electron source comprises a P-type semiconductor substrate, a nano optical resonance emission layer active region and a surface activation layer from bottom totop in sequence. An optical resonance effect is generated by virtue of the nano optical resonance structure and the incident light effect, and a light field and charges are limited in the active region, so that the absorption rate of the incident light is greatly improved, the photoelectron conveying distance is shortened, and the influence of harmful photoelectric emission caused by surface light reflection on the quality of the electron beams can be reduced, thereby effectively improving the quantum efficiency and the quality of the electron beams. The GaAs nano optical resonance structurephotoelectric negative electrode electron source can be prepared by adopting nano-imprinting etching, self-assembled nanosphere etching, electron beam photoetching, focusing ion beam etching and the like, the technology is mature and the stability is high; and therefore, the photoelectric negative electrode electron source can be applied to the fields of large-scale electron accelerators, low-light-level night vision, scanning electron microscope and the like.