The brain structure of Octopus minor was observed by anatomy and paraffin section. The results showed that the brain was divided into three parts according to the location of the esophagus: the supraoesophageal mass, the suboesophageal mass and the optic lobe area on both sides of the supraoesophageal mass and the suboesophageal mass. The supraoesophageal mass includes the vertical lobe, the superior frontal lobe, the inferior frontal lobe, the anterior basal lobes and the posterior basal lobes. The suboesophageal mass includes the brachial lobe, the pedal lobe, the magnocellular lobe, the chromatophore lobe, the visceral lobe, the palliovisceral lobe and the vasomotor lobe. The optic lobe area includes the optic nerve, the optic lobe, the optic gland, the olfactory lobe, the peduncle lobe and the optic tract. Paraffin section, optical microscope and transmission electron microscope were used to observe the microstructure and ultrastructure of the optic gland. The results showed that there was a layer of connective tissue wrapped outside the optic gland, which was located in the optic tract area, adjacent to the olfactory lobe and the peduncle lobe. A large number of secretory cells were observed in the inner part, with a relatively large nucleus and a diameter range of 4-8 μm. The secretory cells were rich in rough endoplasmic reticula, Golgi apparatus, secretory vesicles and vacuoles secreted by Golgi apparatus. The results showed that the structural characteristics of the optic glands of O. minor were similar to those of Sepiella maindroni and O. vulgaris.